There are thousands of Totos installed out there with the Unifit...I have two in my home. They work fine. To install, you have to drill four holes in the floor. The front of the thing bolts to the flange as if it was a regular toilet with a wax ring. Then, once the adapter is installed, you set the toilet down over the adapter. The back part that you anchored to the floor with those 4 screws has slots for a second set of toilet bolts - these fit up through holes in the toilet and you bolt it down with those onto the firmly anchored adapter. Takes a little longer, but is easy.
Those toilets that use the Unifit normally have a gap of 3/4" behind them. So, you'd nomially have a gap. When installing the adapter, you can fudge it forward maybe a 1/4" and still be able to install the anchor bolts at the flange and still not create a ledge with the waste trying to go down the drain...the fact it isn't perfectly centered isn't an issue as long as there's no interference. So, you could end up with maybe 1/2" gap, if you wanted to fudge the whole thing at all.
I'm not familiar with the whole line, but all of the units with the Unifit have an enclosed, hidden trapway (which is the Unifit, which is why they are skirted, to hide it). I have a Vespin and a Carlyle in my home. They all work, it's a style thing as to which one you might choose (along with the price).