Upgrade E-PL5 to GX7?
Personally, I would wait until the GX7 is actually officially introduced and some independent photographer images start appearing. Rumor sites have been known to be wrong and most are just repeating each others rumors. This is a good time for patience.
I have to admit that the GX7, as described, sounds good, but manufacturer claims of improved sensor, etc often don't pan out. The viewfinder sounds good on paper, but remember what Panasonic did with the optics on the GH3.
It may be the best m4/3 to date or it may be something less.