Actually the Aquia II is the newer version! The Aquia I has been discontinued AFAIK. The Aquia III is the same but in the taller "comfort height".

I guess my response is too late for the OP's information. However, I have replaced toilets in three houses. The first house had two BR's and the next two had three bathrooms. First house was our entry level house in the Los Angeles market; we installed two boring Kohlers that performed well and quietly and I never needed a plumber for anything. Our next move up house was a huge jump up in cost, it was almost double square footage but the premium in cost was mostly because it had an amazing ocean view and marina view and this even from the shower in the master bath. In this house we upgraded with Kohler's San Raphael in the master and guest bath and in the powder room, we splurged on the St. Martin (or San Martine?) an incredibly beautiful toilet with what we thought was a pretty high price tag of over $800, which was a lot for that time period (the early 90s) though not so much in these days of the $3000 "hatbox" toilet from Kohler. None of these toilets ever caused a problem, though our plumber who was the BEST, (JEFF of family-owned and run Argyll Plumbing, if you're reading this out there in Torrance CA. it is you to whom I refer as the BEST) warned us that we possibly could have problems with the high-end San Martine but these never developed, at least not while we still owned the home. Because of a precipitous move downward in the income and wealth index by a lot (thanks to very serious mistakes by physicians at the Jacksonville Fl. Mayo Clinic, mistakes that could and should have been caught and avoided, mistakes that served to end my husband's corporate and international business development career with its comfortable income and more important, true meaning in his life, while at the same time our savings got used up and our retirement funds were almost breathlessly depleted while we looked on, heads spinning, and as we are now, the proverbial unhappy campers, saddled with credit card debt run up in a few years time but that will take years if ever to pay off, and forced to be "re-educated" and to deal with new goals not of our making: like living on a fixed income that has little extra for not much of anything and maintaining a home that we'd rather not, since our goal at the time this all began had been to sell the house and return to the West Coast, our real home, but then this "merde" came our way and by God, did it ever hit the fan!) the Kohlers in our three bathrooms in our current home are more modest models, either the Kohler Highline or the pretty little Kohler Santa Rosa. These toilets got replaced a second time though because of the newly introduced comfort height toilet, this a great feature that hadn't been available in 1999 when we moved into the one-year-old home and immediately upgraded the cheapy contractor's grade toilets, and a feature that we would only come to fully appreciate later on (my husband has had both of his hips surgically replaced,plus one knee, so far) and now wouldn't give up for any reason. We are getting around to replacing the master bath's standard-height Santa Rosa and I've come to this dependable forum for help with our decision. Because decisions like this now take on amazing significance. So rather than replace a Santa Rosa with another Santa Rosa, even as pretty as they are, we are seriously considering the Kohler Persuade Curv. I love the look, its slender beauty and the ease of cleaning the look suggests. (I'm not getting any younger). But I hesitated and have for a while. It doesn't seem possible that Kohler could offer that great look (a smooth bowl that jumped forward into the 21st century, leaving behind the tired look that mimicked the pipes, the interior function) and do it at a price point that actually was possibly attainable by the majority of the toilet-needing masses, this from the company that shocked the world (well, I was shocked!) with the $3000 "hatbox" toilet. After many years of nothing but success with Kohler toilets now when we don't have the resources to reverse a bad decision, the wrong choice, after all I've read about the Persuade, I am stuck. Is going with the Kohler Persuade because of the beauty of the look, (and because I internet shopped and found a very very good price) while I bury my head in the sand as to any problems lurking down the road, problems I learned about also on the internet as I researched WHICH KOHLER TO BUY, is all this by definition telling me I'm in a new world here and to tread carefully with my few precious dollars?

My experience has been that the TOTO toilets are hard to beat. I dont have experience with that TOTO model but with the TOTO Drake and it is wonderful. I did some quick internet price search and actually found to TOTO for less money than the Kohler which surprises me because TOTO is known to be expensive.

If it helps, I just had a Toto toilet installed (just the plain Drake). I bought it myself, and hired a plumber to install. The plumber told me he thinks the Totos are the best toilets, and he really doesn't like Kohlers. He said the Kohlers are expensive cause you are paying for the once-great company name, but the company is no longer great. He said they break all the time. Since the plumber had no skin in the game, because I purchased the toilet myself and not from him, I believe he was giving his honest opinion from his experience.