We mainly install the TOTO Aquia. It takes a plumber just a while longer to drill a few holes through the tile.
I've sold and/or installed a few hundred with very good results.
We installed two yesterday in Seattle, and will do one in Everette on Wednesday.
I have the least amount of problems with the Aquia then any of the other dual flush toilets.
Don't buy anything with the EcoFlush pressure assist. I've had 40% of the tanks come back in the first six months. I no longer sell them.
Gerber, American Standard and Mansfield are a few that mistakenly provide that piece of junk.
Caroma does make the 305 bowl that will fit without drilling.
The 270 bowl requires two holes through the tile.