A LOT players use head heavy rackets in doubles. The whole voltric series is quite popular around here for doubles. (Yes 3u) would you consider the n50ii to be head heavy though? It's more even balance isn't it?
Even MX80 although being head heavy, it is no wear near those VT80, VTZF or N90. MX80 will excel as Doubles racket.
N50II is head heavy, not as head heavy as VT80 or N90. It's more like the meteor series: about 300mm bp strung and just with factoy grip. VT80 and N90 are in the 310-320mm region. My Carlton VT S-lite (which is head light) has the same bp of 300mm but weights only 89g as opposed to N50II 98g - There's a substantial difference between the swing weight of the two. It's great if you like playing doubles with VT80 3u and it works for you. We have quite a few vt80 users here too, no doubt it's a popular racket.