From what I've read, it's the reflector ahsupply's fixures come with that give them the edge. Not to mention the awesome rav's from users and the awesome customer relations.
If you're going to have live plants, go with the 2X55 kit, if not, go with it anyway because sooner or later...you will .
I have a ah supply 55 on my 29 I liked it so much that when I bought a 90 I got 2 2x55s. If I had to do it again I would still buy the ahsupply. Kim the owner who you talk to on the phone is great to work with. I think that the reflectors that ah uses makes the difference.
2x36 might be perfect. 2x55 is too much, unless you add in separate swtiches so you can turn one light off most of the time, just have it on a few hours at noonish. 2x36 gives you a bit more length, the 1x55 is just a bit short for a 30" long tank, leaves dim edges but only the top 3 to 4" only noticible when plants grow and trail along the surface.
I agree 110 watts of light on a 29 is ALOT! If you really know what you're doing with CO2, nutrients, etc. and are willing to stay on top of it you could try it.