Here's a thought. If she's looking to find fault with it, she will, regardless of the technical facts. If she's open-minded, and loves saving water, she will like it.
Here's a video of it flushing. Read the woman's complete comments (i.e. the "show more" section); she put nasty guacamole on and in the thing, and let it dry, and the toilet mostly got it off except for one dried bit. You're not going to let feces sit that long -- at least I hope not.
The flush seems underwhelming -- no big RUSH of water -- but it does the job and evacuates the bowl. Key things to take away from the video: Note the nasty green water with junk floating in it. Notice it all disappears and is replaced with completely-clear water, meaning the entire contents of the bowl was evacuated. Nothing left over.
Here's her review from the big retail site we don't talk about on here:
"We upgraded our toilet because our county offered a rebate for high-efficiency toilet upgrades. The toilet that came with our house was made in 1949 and gets clogged all the time. We initially planned on getting the Aquia dual-flush but we found out from local store clerks that "streaking" is a major problem. [MY EDIT: TOTALLY UNTRUE. NEVER TRUST THE GUYS IN THE STORE -- THEY KNOW NOTHING AND OFTEN GET COMPENSATED FOR SELLING PARTICULAR MODELS] It was also quite expensive - at least $200 more than this model. [ONLY AT RETAIL, AND THE ONE-PIECE COMES WITH A FREE SEAT.] We had a hard time deciding whether or not to buy this Drake model since we couldn't find reviews anywhere and my husband kept worrying that 1.0 gpf might not be enough water to do a clean flush.
Installation was pretty straightforward but my husband had to make a couple trips to the hardware store because he bought the wrong-size wax ring and hose. So make sure you measure everything once you take your old toilet off.
UPDATE (2/19/2013): We have been using the Drake toilet for 2 months now and we are very impressed with it. It does a clean flush each time. The cyclone flush swirls water around the sides of the bowl, thereby cleaning it. It's actually pretty cool to watch. The suction is amazing...in fact, we have gotten rid of our plunger for good. We initially thought that 1 gallon of water would be too little to do big jobs but we were mistaken! This toilet is also noticeably taller than our old one and we're loving it. We highly recommend this model.
We got the
[TOTO SS114 Slow Close Seat] (sold separately) and we think it's great. No more slamming the toilet seat accidentally.
For the video demo, I used some spoiled guacamole. Normally, the toilet doesn't leave streaks/stains but I let the guacamole sit in it too long and it had actually dried out on the sloped surface. Hence the little stain left after the flush.
By the way, there is no reason for this toilet not to fit on your space, even if you're off by 1/8 or 1/4" in your measurements. Remember that the flange opening is 3" or 4", and the outflow pipe on the toilet is 2-1/8". Normally, you center that over the flange opening, but the reality is that it doesn't have to be, because there is more than 3/8" of space between the perimeter of the outflow hole and the perimeter of the flange opening. So you (or a smart plumber) can "cheat" the bowl forward as much as 3/8" by positioning the closet bolts a little further forward on the flange and taking advantage of the design of the openings for them in the porcelain. Most handi-hacks don't know or think of this. This is why you always dry-fit a bowl carefully, and put the cover on, to make sure you like how it sits before installing it permanently.
