Well, I just might need to face a fact here. I don't have the equipment or patience to properly test every aspect of this tuner!
I did some fooling around with this week. Verified that the "tow" options sort of do what I expected, but testing the DEGREE to which they do it is difficult. In the driveway, I was able to verify that having the "tow" option set (LOAD OFFSET variable set to "2") definitely changes the throttle tuning. Comparing pedal position to throttle position, the throttle was moving about 4% more than stock under driveway conditions. Just holding various constant pedal positions, the throttle position would be greater and RPM woudl be greater. I have no idea if the change is linear or not. I was dealing with VERY small pedal positions due to no load.
I did some more testing on the road, but ended up logging the wrong values and it was useless data. Pretty sure that at the very least that 4% follows through. It's probably just modifying the raw pedal position values to make it look like you've applied more throttle, and make it feel to you like you're not using as much pedal and give you the illusion that you have more power for towing.
Ran out of time, and left it set that way. I haven't driven much this week. (in my own car, anyway) But, driving around last night, I noticed that the increased throttle position is actually a little goofy in some ways. The very low pedal position is very touchy, and it shows itself when you're puttering around a parking lot, or sloooowly slogging off of a traffic light in 2nd. You know when you're way low in the revs, and you know you need to baby the throttle, but you ARE trying to accelerate a little bit? Yeah, that. In that situation, with LOAD OFFSET = 2, it just sort of leaps past where you want to be and bogs. I'm sure it's something I'd get used to after a while. But, being used to the original calibration, it was weird.
Note that I don't presently have the exhaust settings enabled (FUEL OFFSET 3 and 4, I think those are). The combination of those settings being correct AND the LOAD OFFSET... that might actually work better. So, I have more experimenting to do.
The good news is that this device clearly DOES make changes. I had someone who had autocrossed my car before do a couple of autocross runs in it last weekend (with the first set of settings I had in it) and he commented that the car felt peppier and more responsive. So, it's not in my head.
I'll keep playing with it. And when I get it set up to where it "feels right", I'll give it some time to settle in, and then redo my acceleration test and report back on that.