I have only had my kangaroo for a few weeks, but really do love it.
the seats don't have head support, but are very comfortable hammock-style seats. they can lie almost flat fairly easily - they adjust quickly by sliding back and forwards, and you can adjust the angle of the backrest simply too, so you could have your 11month old reclining nicely. I'd probably still use a travel pillow/neck support at that age, I suppose.
I don't bother changing from 1 to 2 seats. I have both fitted and leave it like that, as am dropping off the heavier child, and can't be doing with the faffing (althugh easy, can't see thepoint). If I were dropping off dd2, then I might well change to single seat in the middle to carry dd1 as she is quite big and heavy.
the steering of the bike I have found fine - big corners take a bit of getting used to, and it is actually easier to "let go" of steering like a normal bike (I assume, I'm not actually a bike rider!) and just hold one corner of the handlebars rather than trying to steer fully. The back peddling I have found very easy to get used to (again, maybe because I am not a bike rider?), and this is much easier/safer to use than the front brakes, which are ok for final slowing but can be a bit abrupt when stopping form speed.
I haven't yet used it in the winter months, but I could see me doing so (apart from serioulsy bad weather). the girls willbe snug enough - the cabin is really weatherproof, so it is just a case of getting me weather proofed too. I am hoping by that time that it is such a part of my routine/fitness that I do not want to give it up!
There is a blog that I read carefully when considering which bike/trike to buy - hold on..... this man has a kangaroo, and cycles in all weathers up in Scotland - that convinced me it was weatherproof enough for the girls!
I think I cycle about a 4 mile round trip for my pre-school run (so 2 miles with dd1 (22kg) and dd2 (10kg) and 2 miles with just dd2), and it is going well so far. It take sme about 30 mins each way, and does include a couple of small (well long, but not too steep) hills, which are ok as long as you keep momentum!