#3
they're effectivly the same guitar but the ex is a newer model and has emg designed pickups instead of ibanez pickups, both should be good interms of quality, just try them and get the one you like most
#4
They're the same exact guitar

however: The MH has the Ibanez INF3/INF4 pickups, while the E has an EMG H4/H4A combo.

One isn't higher quality than the other. The only difference between them is the pickups.

I have never seen the new RG321's though - all the ones I've seen have the old bridges - I haven't seen any with the new Gibralter bridges yet. Either way you go with the pickups, they're both bound to be great guitars. Given they're still right around the $300 range, they should be a real bang for the buck. Be warned though, it's very likely that Ibanez will bump up the price to $350 to compensate for the EMG's and the Gibralter bridge.
Spin 'round carousel when your horse isn't screwed in.

My band:
Fractured Instinct
(For fans of Death/Groove/Prog Metal)

Ibanez RGA42E
Ibanez S420
LTD H-301
Ibanez RG520
Peavey Predator USA
Douglas Grendel 725
Line 6 Pod HD500X
#5
What's better for metal
And has a
Better
Sound plus should wait for these to
Come
Out or should I get the older
Model it's coming-out at the end
Of
The summer my birthday is in 20 days I think
#6
Was your cat stepping on your enter bar? That was difficult on the eyes.

I would wait for the new ones. The new bridges are designed to be a lot more comfortable than the old ones.

As for what's better for metal, that depends on what you want to sound like, and (most importantly, and much, much, much more important than which one you get) what amp you have.

I've had both the EMG HZ's, and the INF's, and I can say that the EMG's are warmer, and more full sounding, while the INF's are every harsh and biting. Not in a bad way though, they're just really bright and aggressive.

As far as neck pickups go, the INF3 is not as good as the H4A. It's less defined; more muddy. If they're going to be the same price, you should get the one with EMG's, in my opinion. Even if you don't like the INF's or the EMG's, they EMG's will have more resale value if you choose to part with them.
Spin 'round carousel when your horse isn't screwed in.

My band:
Fractured Instinct
(For fans of Death/Groove/Prog Metal)

Ibanez RGA42E
Ibanez S420
LTD H-301
Ibanez RG520
Peavey Predator USA
Douglas Grendel 725
Line 6 Pod HD500X