You know the sensation and the G2X is the same thing more or less, except for the qhd display and maybe some other small disfferences.
All the described issues are software issues which will easily be fixed with a patch. If you recall the iPhone4 kept restarting as well and although it was a hardware issue noone rushed to return it who knows maybe its the same problem with the wifi and cell shortage on the G2X, put a plastic cover around it see if it helps. There were also battery problems at the launch of iphone 4 and were fixed with an update patch.
I Dont know, the G2X will be my first android. For me, the sound of stock sounds better than Sense but the qhd sounds better than the WVGA but the 4" screen sounds better (to me) than the 4.3" but the sensation has dual flash but the G2X is not locked but the Sense has LED notification but but but but but but but..
There always is a but
IMO They both will be good phones! but I too am debating returning the G2x and waiting for the sensation as I said on a different post I can wait for software updates but screen bleeding is hardware and thats a problem.