I know that you get a more shallow DOF and better high ISO performance with a full frame over a crop, but with good lenses on either is there really much of an IQ difference all other things being equal. I do get great results with my T1i, but I do see some ultra-great results out there that my camera just isn't capable of. The sensible option is to remain with my crop-inspired lenses and maybe go to a 70D or the next Rebel, but the 6D seems pretty cool.
I agonize over this stuff because I'm the opposite of a gear-hound. I'm a minimalist who tries to do the most with the least so it's quality over quantity. Thank you in advance for your wisdom.
All else being equal, a photosite is a photosite. A FF camera has a larger area, BUT...
Has shallower depth of field (NOT always a good thing, ESPECIALLY with long lenses)
Wide angle lenses are WAY more expensive (there are superb crop lenses Tokin 11-16 for example)
lenses are not as long...
There are a lot of people jumping on the Micro four thirds bandwagon. check out Natureandphotography.com
The author there has ditched FF for smaller, far more usable gear. A camera is useless which is too bulky to use. If you ever feel like not picking up your camera because it is too heavy, consider the true price of FF...