EOS 6D and cheap glass

So the Sigma 17-50/F2.8 (OS HSM whatever) works on 6D.  But even I can shoot with the 6D, the cropped picture file is pretty small (<8Mpixels). Hmm.

I love this lens, hate to part away because of having the 6D. Replacing it will cost at least another grand, dang.

on the fence...still.