I think you have the pro's and con's pretty well covered. You have the experience to understand them pretty well, after all.
Touring around with a smallish motorhome is certainly possible, though less convenient than using a tow vehicle. How much less convenient partly depends on the size of the motorhome and the area you're touring around in. I've done a fair bit of travel with my 32' class C and no towed vehicle, and have not generally felt the need to get a toad; however, that's partly because I've chosen to go places where having just the motorhome works out relatively nicely (either because things are within walking distance, or there's public transit available, or there's reasonable parking, etc. available for the motorhome).
Launching a boat from a trailer behind a motorhome might be problematic with some boat ramps, depending on the angles and such. It would stink to have to dip the back end in the water much, or to have the trailer angled at a really steep angle down because the part of the ramp the wheels are on is less sloped. I think it might work out better to install a front hitch for boat launching and retrieval purposes, though switching the trailer around end for end would probably become annoying.
