I'm using a 50' cheap GE HDMI 1.3 cable with my Epson 3010 with NO issues on 3D nor anything else. Works PERFECTLY.
In fact, run is actually longer than this as the 50' cable actually connects to a Pioneer 1021 receiver and then goes out via 6' Philips cables (5 year old Sams Club specials) to my Panasonoc bluray and XBox 360.
So overall its at least a 56' run not including the path through the receiver.
BTW prior to getting the receiver, I did have the 50' cable directly between the 3010 and BluRay with no issues.
Your mileage may vary, but Ive been very happy with the result. Virtually never had a problem with the BluRay and projector syncing 3d, perhaps twice, but on both cases it appeared to be a case of the receiver being confused and doing handshaking improperly, due to the receiver and projector previously being set to the XBox 360. When I popped in a 3D BluRay, the receiver switched input to the BluRay automatically (as it is setup to do) but the BluRay didnt detect the pj supporting 3d. All I have to so is manually tell the reciever to switch to the BluRay first and I never have a problem. Probably just a timing thing.
But no issues I can attribute to the cable.
I have heard that other projectors might not do as well on such a long cable. Reportedly, the Epsons have pretty good HDMI error correction and strong signal.