Can't tell you about the tree-version, but they do bloom a lot, even since they are small & young. And they start blooming early in the season. Mine are still very young, but are alaways covered with flowers and never had any health issue (I do not spray my roses).
However, they need sun to bloom (4 hours or more), as they are poor performer in a shady spot. I had to transplant those in the shadow, placing them in the sun.

I have heard about double knockouts. True, not about the tree version, but they are supposed to be completely carefree, except for heavy needed pruning in the south.

My DKOs have never been completely carefree. They get rose slugs (no other roses in my gardens do), weird white-ish spots and canker worse than any others in my beds. I still love them for their constant bloom and full shape. The tree forms would be lovely, but just don't expect completely carefree.

I can't quite picture them as standards. I mean, they don't cascade down and are rather upright. The flowers are nice but if you don't deadhead them they don't always drop and end up looking like wads of brown messes.

You are right Rita. I decided against them for that reason. They look awkward and way too stiff. Thanks everyone for your input.

I am all for it.

Mine was from Home Depot two years ago. It performs like a regular KO, and doesn't look stiff at all because I trim it often to keep the round shape. Shoots that are pointing out and downward are welcome, remove the ones that are growing toward the center and the overly strong ones. It will gradually get rounder and rounder every year.

In the winter, I put it under the deck against a wall, roughly cover the graft union with an old winter jacket or sometimes a blanket. It never had any die back and always was the first to wake up in early spring.

Health wise and vigor is already well known for this rose. I under plant it with the miniature rose Green Ice, and they are the hardest workers and the most reliable in the garden. I used to have Gene Boerner then Playboy standards, keeping the round tree top shape wasn't hard, it's the health issues made me replaced them and decided to keep KO.

The only thing with standards to me is to keep them straight, and to protect them from strong winds. Remember to water too.

Here's mine in late May. It bloomed nonstop for a month, rested for about two weeks and now it's covered with new growths and tiny buds, getting ready for July 4th! I plan to give it a much bigger pot next year and add cascading annuals underneath it.
{{gwi:295533}}

I say this rose is worth every penny you will spend.

Oh wow, that is beautiful! Hmmm... can I afford more roses? Well, let's see, eggs for dinner all week, lol!