Upgrading to full-frame will not make me a better photographer any
more than a computer with a bigger screen will make me a better
writer. Thus, full frame or not full frame, to me, is irrelevant.
Your mileage, of course, will vary.
When I bought my 20D, I did not wake up and say, "Gee, I think I'll
go out and by a 1.6 factor digital SLR." When I shopped for my
camera, I bought a product that I thought best fit my needs and
offered the flexibility for which I was looking. I paid no heed to
FF vs. crop, even though I could have afforded a 1Ds.
For my next camera, I'm more interested in its response, its
autofocus capability and accuracy, ability to shoot at 5 FPS or
faster, its methods of metering, and other features. If it's FF,
that's just swell. But if it's a crop, then so be it.
In the end, to me, there's really only thing that matters: Does it
make good pictures?
Just my $0.02.
--
When I ask which Canon lenses are best,
people tell me to 'go to L.'