The MTX is probably the higher quality amp as distortion is a little lower and S/N is quite a bit higher. While the Rockford is about 10% more efficient and puts out about 200 more watts.
For your application where the extra power isn't really called for, at $80 price difference I'd have to say the MTX would be the one to go with.
The MTX is $300 compared to $380 for the Rockford.
If you have the HE and not HE2, you may even consider going with an MTX 4250D at $200.
It puts out a little over 400W RMS into 2 ohms. While the HE 12s can only handle a little over 200W apiece.
Looks like a nice match to me. Although it can can never hurt to have too much power if used wisely. And you get additional expansion capabilities, say if you wanted to add 2 more subs or step up to more powerful ones.
Just a few things to consider.