I think Mike's right on this - it depends on what your expectations are. One of the guys in my carving apprenticeship class just bought an 18" Rikon, and he loves it. Mostly what he's doing is roughing out very large carving blanks, so extreme precision isn't what he's after.
In my case, I've an older Delta 14" with a 2 HP motor and a riser block, and I use it to resaw 10" wide or more mahogany all the time, with good results. I suspect, however, that I'd have a fair bit of difficulty if I tried that with hard maple. I also use a 3/16" wide blade and a point fence for re-sawing, which cuts down on the required horse power and force against the saw structure considerably.
Moreover, I don't attempt to cut veneer with this saw. Lots of the magazine articles show methods to do this on a 14" saw, and while I believe that it's achievable, it's also extremely demanding, at least when I've tried it - you have to have an extremely well-tuned saw and be patient.
In regards to re-sawing big lumber, you might want to look up someone with a WoodMizer portable sawmill. I had some 24" wide 12/4 mahogany that I needed re-sawn, and there was no way to do this without ripping it into pieces about 8" wide and running it through my equipment, which I wasn't prepared to do. The Woodmizer guy I found was willing to do it for $1 a linear foot, and he was remarkably accurate - within a 1/16" in thickness.