I have a Korky installed over at my mothers home in a Cadet wall hung that has been in use for 15 years.
You can use any fill valve in a Toto; there's plenty of options there.
The Fluidmaster can overfill the bowl, but most plumbers wouldn't care about that. It's water down the drain, which can add to a water bill.
All flappers need replacement at some point. Korky also makes replacement flappers for all toilets. If you are having problems with flappers, then there may be a chlorine tablet in the tank.
We installed a Kohler Memoirs one-piece toilet the other day that was just junk.
The bowl fill alternated between full and party full. Therefore the flush varied between flushes.
The bowl was not even , so sometimes the water line was smaller on the left.
The bottom of the bowl was uneven, so I had to shim on two opposite sides.
Water sprayed on the wall with the tank lid off.
That was a top of the line Kohler product.
I've sold thousands of Toto products over the years, with less then 1% returns. Nobody else can come close to that.
Sanagloss has been a very good product. Like I said in the previous post, the ones in my home look like the day they were installed.
I've been selling Sanagloss since 1998, and they are all in use.