Toto Aquia Wall-Hung

I'm getting ready to buy one of these for my bathroom remodel. Anyone install one?

I read the spec's - looks like I'm going to have to bring the wall out the width of a 2x4 - otherwise I'd have to remove part of the bottom plate for the the waste pipe?

Once than tank is sealed in the wall - the flush valve replacement looks kinda scarry too.

I haven't done an install, but I have seen one done. The person knew what they were doing so it looked relatively-straightforward.

Replacing the flush valve seal is actually pretty-straightforward: you remove the actuator plate and the actuator, reach in, remove the thingy that is holding the valve in place, and remove the valve by bending it forward and sliding it out. You replace the rubber doughnut and put it back the way it came out. Same thing for the fill valve if you ever need to fix it or to adjust the water level.

They have at least tried to make it easy, and folks routinely put these things behind nice, finished tile walls, confident that they can replace anything that matters by getting to it through the opening by the actuator plate. If the tank cracks, that's another story, but apparently that is very rare.

I'm about to do the same, and I've got some questions regarding the best way to configure the plumbing rough-in. The outlet bend could go vertically into the floor, where there would be a 90 transitioning to a horizontal, or I could angle it 45 degrees and transition to horizontal under the floor with a 45. Under most circumstances, I would think that the latter arrangement would be preferrable for drainage, but toilets are weird beasts, relying on siphoning to do their job, so... which way is best? Once it's under the floor, it's a straight shot to a 4" drain which continues in the same direction, and this is the last fixture on that run.

Are there any other gotchas with these that I should keep in mind? For instance, should I strive to not locate the vent within a couple of feet of the outlet bend? Should I maintain 3" for some minimum length before transitioning to the 4"? The reason I ask is because that 4" needs a cleanout, and the ideal spot to put it would be into the same bump-out that houses the concealed tank, but this would require me to transition to 4" pretty much immediately, and the toilet bend would most likely discharge into the "bull" of a vertical street wye with the cleanout out the top and the outlet at the bottom.