What kind of height are you needing? We avoided the headbanging issue with a slideout. Sure, spouse would bang it, but it would slide in instead of drawing blood.
Totally painless and cuss free. (We used a GE Monogram model.)

Of course retrofitting it into existing cabinetry wouldn't be the easiest thing.

Lowes carries one that is a half-circle arch (think it's a broan, but not sure), but I don't think the cfm is very good. Very nice looking hood, though.

Kobe makes some that are a bit rounded. Maybe just make your husband wear a helmet in the kitchen.

Here is a link that might be useful: Kobe hoods.

I have the Ventahood Nouveau Pro, which has a rounded lower edge. I've never bumped it though.

Here is a link that might be useful: VAH Nouveau Pro

I forgot how fast this board moves! Thanks everyone for your replies. I will check out the suggestions. It is funny how you are never really finished with your remodel, there are always some things you want to change after living with them awhile.
Clare

I have a Vent-A-Hood with an "emerald lip". It's not rounded, but the corners are not as sharp.

However, I will say that we have not had problems with head hitting. Our hood is 24" deep and is installed 30" above our cooktop (per specs). We are a rather tall family but we do not hit our heads on it. (I'm the shortest at 5'10", my DS is the tallest at 6'6".)

Here is a link that might be useful: Vent-A-Hood SEPH18 Euroline Pro with Emerald Lip

My Rangecraft Viser has softly rounded corners. I've hit my head on it without bonking anything sharp as there are no exposed metal edges anywhere. And it's USA made. :)

I don't have a pic right now, but my hood is from Sirius, an Italian co, and is completely rounded.

It is 7 yrs old now, and my 6'2" dh has never bumped his head.

here is the current model--mine is only slightly different:

Sirius range hood

Thanks for the additional suggestions and especially the pictures. I am still doing research. DH is 6'2" and even has drawn blood on that "blank" range hood. I don't have a problem with being only 5'3". It is 29.5" above the counter and 21" deep.
Clare

We have a Best by Broan wall mount hood with rounded corners.

I like the looks of the Rangecraft Viser and Best by Broan. Don't know if any of them will work. I will leave that up to my engineer DH.
Clare

I have a Zephyr Savona that is a half moon shape in the front.

The specs for our 24 inch deep Best hood
stated that it could be mounted up to 36 inches off the stove/range top.
We mounted ours at 33.5 inches above the range
and had no problems with head bumping,
even though we are a tall family.

I suspect that your husband's head-hitting problem will be solved,
regardless of whether or not you pick a hood with soft edges,
by mounting your new hood 33 to 36 inches above the range.
If you have sufficient cfm, it should still draw fumes just fine.

Our hood:

"The specs for our 24 inch deep Best hood
stated that it could be mounted up to 36 inches off the stove/range top. "

You could also mount it 48 or 60 inches.

It will not be very effective once it is more than its width or depth above the stove.

You can look into a custom hood (they are not all that hard to make) or an insert for a custom hood.

Using an external remote blower makes a lot of things easier.