Replacing in-wall, wall hung toiliet w/ different water consumption

[FrankFont]

I am replacing three wall hung toilets in my home and am struggling to figure out what new toilet will fit. The walls are tiled over and although I can replace some tiles I do not want to replace the wall tank. I am making the change because I want to add a toilet with bidet and I want to use a different toilet for the bidet.

The current tank is a 1.6/0.8 GPF and I'm wondering if I can get a 1.28/0.9 GPF toilet. Here are the specs:

Geberit 111.798.00.1 Duofix Concealed Tank Carrier
2 x 4″ wall stud
Dual Flush 1.6 / 0.8 GPF (6 / 3 LPF)

I want to add a Toto toilet with bidet seat. I would prefer to get the MH toilet with bidet (1.28/0.9 GPF) because I like the shape, Tornado flush and bidet option. I'm also thinking about Aquia or Maris (1.6/0.8 GPF), although I feel that they're smaller and have weaker flush (dual flush). Aquia and Maris are definitely compatible according to Geberit - for the fit and for the GPF.

When I talk with Toto, they say that the holes on the Aquia, Maris, and MH are the same. For Toto, if you use a 1.6/0.8 GPF tank with a 1.28/0.9 GPF toilet, it's fine. Talking with Geberit, they will only say what has been tested and confirmed (Aquia and Maris).

Obviously I have spent way too much time on this and would appreciate any input.
Many thanks.

 

[ss3964spd]

Frank, I simply used a Toto Aquia 1.6/0.8 elongated bowl with my Geberit 1.6/0.8 carrier (2X6). It flushes just fine and doesn't splash.

I, too, installed a bidet seat. A Toto, I think the C200. Love it., especially the feature that pre-wets the bowl so solids don't stick to it. It works.

As the water connection for the Geberit is concealed, and if you didn't pre-plumb for it, how are you going to supply the seat?