The new line of MTX subs are far more superior than the old line... Its like comparing the Thunder 8000's with the new Thunder 5500's.
This is the one you are gonna want
T5512-44 12" Sub Dual 4 Ω 30-150Hz 300watts rms
As for DVC and SVC... Since you are running only one sub, then I recommend a Dual Voice Coil sub. It will allow you to knock your amp down to 2 ohms. What amp will be pushing your sub?
If you are going to be running it off that amp along with your components then you are only going to get 160 watts rms out of the other two channels at 2 ohms. You wont be getting the 300 rms you are looking for.