Bumping this up! I have a small collection of 5 hydrangea macrophylla. I'm going to post a link to the variety and explain the history/ location for each, along with an update.

Winter was pretty mild this year, but had several sudden dips into cold temperatures. I'd say overall it was more like a zone 7 winter, but it was pretty shocking for plants as it would go from 70 degrees (Fahrenheit, obviously) to low-teens and single-digit temps very rapidly, and that happened several times. I think it stayed above 0 degrees all winter. I have alkaline, clay soil so blooms are pink.

Everlasting Revolution (Hokomarevo): two planted, both in full sun (south exposure). Plants Nouveau link This is the second winter I've had them, both years they've die back to the crown but come back well. These are very tiny little hydrangea bushes and they definitely are dwarf and grow very slowly-- the "mature size" of 18 inches is probably at least another year away. The whole plant is miniature compared to my other hydrangeas. They both have broccoli. I intended to move the one that gets more sun this year as it didn't bloom last year, but I didn't get around to it-- and it appears to be doing better! From past experience, the blooms are beautiful, though small. They start pink and white and gain green streaks as the blooms age.

Pistachio/ Horwack. Western exposure, pretty shady and fairly shielded. Pistachio link. I don't think it died back to the ground, but I forgot to check on it early when it would be easy to tell. Again, second winter in my yard, and growing well, but not very quickly. The blooms are already opening (whether that's because it's sheltered or because it's an earlier bloomer is uncertain), and are pea-green as they are always until they mature. Will develop an intense fuchsia color with green accents as the bloom matures, no blue center in my soil. It's starting to demonstrate the iron chlorosis coloring, on new leaves, it's interesting that it doesn't show that coloring until the blooms form and are opening (it's not on the first ~30 leaves). The plant continues to grow and bloom with no real maintenance on my part, and I like the look of the yellow leaves.

Together (RIE05)- planted on the north side of the house, gets sun from early morning to about 10 am. Together link. I got this last summer as a mildewy plant on clearance. Whether because this is heartier, or because it's in the ideal position, this was my only hydrangea that did not die back at all, so it's the biggest. Has lots of broccoli. No experience with the flowers yet since it was an ugly duckling when I got it.

Peppermint (RIE14). North side of the house, essentially no direct sun. Peppermint link. Also got this last year, but it handled the crowded box store conditions better and didn't have mildew. This died back to the crown overwinter but came back really well and is nearly as large as Together. Has fewer groups of broccoli than Together, but the clusters it has are HUGE. I am looking forward to the blooms, they are very impressive.

Everlasting Revolution I can definitely confirm blooms on new and old wood. Peppermint and Horwack bloom on new wood, and Horwack also blooms on old wood (Peppermint and Together did not have a second flush of blooms last year, but they were recently transplanted).

Together may or may not bloom on new wood, but it's definitely showing broccoli at the same time that the other plants that died back to the crown did. Together may be more cold-tolerant than the other hydrangeas I have.

None of the plants are showing signs of downy mildew this year, and there's been a lot of rain.

Overall, I'm pleasantly surprised with the new entries, and pleased that both Revolutions are gearing up to bloom this year! It matches your experience, though--all of my plants are in your "reliable" group.

Those are good picks and probably the best current dwarf/semi-dwarfs!

Today I saw broccoli on Izu no Hana and Tivoli Red! Both were planted last year. Recent purchase of Sumida no Hanabi leads me to believe it might be the pigmentless version of InH.

springwood - u have an enormous hydrangea collection!..love macrophyllas but they've disappointed me..only Twist-n-Shout has flower heads..have 6 Quick Fire paniculatas..4 planted fall 2014 & 2 fall 2015..they look great..do u grow paniculatas?

Macs are a definite PITA with the freeze nonsense. I have a bunch of paniculatas though, can rattle off the names:

PeeGee tree form (2)
Vanilla Strawberry (2)
Limelight (2) + 1 tree
Little Lamb

Little Lime
Great Star
Quick Fire
Sweet Summer
Fire & Ice
Phantom
Snow Mountain
Pinky Winky

All do fine and have their own character, act as centerpieces in various places and once at size they help shade macs, the soil, etc.

Should've known that u would also have a paniculata collection haha..I have Quick Fire, Pinky Winky, Limelight, Tickled Pink & Tardiva..so great to see flowers on the way without all of the hassle..

Since the original post, a small number of broccoli florets have come forth on:

Grateful Red, Wedding Ring, Everlasting Garnet, LA Dreamin' / Mathilda Gutges, one White Out, Stargazer, Izu no Hana, Purple Tiers, Tivoli,

Fuchsia Glow and Double Dare are continuing to churn out buds as the stalks grow. DD is very compact in stature.

A more complete list of what has nothing yet (some may see planters or be given away):

Pink Shira, Mme Mouillere, Queen of Pearls, You-Me Romance, Expression, Big Daddy, Lemon Daddy, Charme, Merritt's Supreme, Mareisii Variegata, Snow Storm, Blue Heaven, Blue Wave, Perfection, Red Sensation, Firelight, Lemmonhoff, Early Blue, Black Together, Early Sensation, Zebra, Princess Lace, Hot Red, Edgy Hearts.

Flukes (supposed to bloom but nothing yet): Everlasting Jade/Ocean/Opal/Pearl/Harmony, LD Rhythmic Blue

All other ES, F&E, and Let's Dance series are putting out at least one flower per plant, plus staples like Coerulea Lace.

The following were not doing so well after the freeze and some switches were made (removees will live in 22x24" pots currently being sold at Sams Club):

Trophee was removed and replaced by Ayesha (bought last year)

Blue Heaven was replaced by Lets Dance Rave (2016)

Blue Wave was replaced by Lets Dance Starlight (2015 mail order)

Doublicious was replaced by Lime Lovebird (2016)

A Fantasia was replaced by Firefly (2016)

Presiosa was replaced by Oakleaf Gatsby Moon (2016)

Lemon Daddy *may* be replaced by a Bloomstruck

How are the everlasting revolution and LA Dreamin doing? Curious as to how "Reblooming" they really are. I bought two LA Dreamin this year, one growing better than the other, but both with no blooms other than what was blooming when they were purchased. I've heard that can happen first year planted.

They aren't rebloomers, per-se, but can bloom on new growth (a.k.a. at least once, even if killed to the ground by winter or late freeze). In the north, this translates to a bloom time of mid-July, and by the time the blooms are spent it's early September and the plants are already beginning to wind down for Fall bud production. Take that information for what it's worth.