floor mount back discharge toilets

Does anybody have experience with the floor mount back discharge toilets. I am thinking about putting one in my basement. Is a 2 by 6 wall big enough for them? Are they hard to install? It is for my 4 year old so are they the same height as the standard ones? And how well do they flushconfused: :

Most of the floor mounted, rear outlet toilets work fairly well, they seem to be pressure assist toilets nowadays.

Gerber 21-310
American Standard Yorkville