I have PianoTeq, and I have personally tried Roland's V-Piano and tweaked some of the modeling set-ups and characteristics. It's stunningly amazing, without equal. Sorry, there's actually no comparison whatsoever. (It's like saying I picked up a plastic toy "dinosaur"-shaped piano and I want to compare it to a Steinway.)
What you can do with the modeling capabilities built into the V-Piano is beyond compare. Yamaha, Steinway, Ivory, PianoTeq, Garrisan, or any other sampled piano (or even REAL piano) will never sound as good for performance and/or recording purposes.
While the V-Piano is not that easy to move around, it's a heck of a lot more so that a grand piano, and a whole lot more versatile. If there was one keyboard in the whole world I could have, it would be the Roland V-Piano. I'd even take it over a Steinway or Bosendorfer full grand (unless I could sell them and buy a few V-Pianos!).
If you've never actually sat down at a V-Piano and spent some time with it, you really ought to. It's the most impressive piano in the world. I especially love changing it to a 9-foot grand, with triple-strings made out of all silver, then re-shaping some of the hammer felt and sounds.