I had a Micro E-Mag, with a short vert feed tube, and blowback was a serious issue. (if you use a warp feed, it's not a problem)
I just got an E-Mag, with a hopper-left body. It feeds quite well. I will eventually add a warp feed to this gun as well.
BTW, don't be so dissapointed with a Crossfire tank. It'll perform well on your E-Mag.
E-Mag ~ Warp, 88/3000 Flatline
AutoMag Classic P/F H/L
GenX 3 'Cocker ~ 68/4500 Conquest (my Son's gun)
Spyder TL+ LP, eLCD, PE 88/3000