First I just want to dissagree with Julian on this one. MTX makes some bad ass amps and if you think otherwise, well you shouldn't be in here.

Second, Tim I would run just 2 subs. Alpine calls for :
Recommended Sealed Box Volume : 0.55 – 0.8 cu. ft.
on the 10's so it should sound fine. Running just 2 subs will allow you to get the full potential out of the amp since running 3 will only give you 2.6 ohms and barely allow you to give the subs its RMS power (300) I think feeding each sub 500 RMS should be fine, I read the 12's can take 500-600 rms all day long and they have the same power ratings as the 10's so I dont really see a problem. You can always turn an amp down. If that doesnt please you well I would either
A) Get another amps
or B) Maybe trade in for the 12's.

I really dont know what your main goal is here so