We have an Ultimate (one-piece) and a Drake (two-piece), the former for longer. I don't think the Ultimate flushes as well as the Drake. They have different flush valves, and I'm not sure if that has any impact. I sort of think that the difference in heights is the key. The slightly-taller two-piece has more head for the flushing action.

With the Ultimate, I hold the flush lever down until the trap glugs when I'm worried about it flushing successfully. With ours, if you don't do that, it takes a plunger rather than a second flush.

I'm still very pro Toto. My parents have an Ultramax and an Eco Drake and don't have any problems.

I went through a 6-month toilet saga at my office, too. It's an 80's vintage building and we were doing a space refresh as part of renewing our lease. I gave our contractor specs for Kohler or Toto 1.28-gpf flushometer toilets to replace the 10 toilets on two floors. The plumber chose Kohler and they were installed. And they didn't work, taking two flushes often. Kohler brought in a regional engineer, they tried different flush valves, and we had them put in one Toto next to the Kohlers in one restroom. What they concluded was that the building plumbing didn't have enough capacity to provide the 1.28 gallons quickly enough. They also said that some of the fixtures had casting problems. We found that, while there were a lot of reasons for the Kohlers not to work, the Toto just worked. We now have 10 of them (with Sloan valves, FWIW).