Alpine MRP-M500 + SWR-1242D. Good Match?

I'm looking to complete my "All Alpine" system I've been working on for a while. I have the X100 deck and just purchased an M500 amp. For a sub I was thinking 12" Type R. Now since my amp runs 500 watts RMS at 2ohms and only 300 at 4ohms, I was thinking I should get the 4ohm sub and wire it so that my amp is running at 2ohms. Am I on the right track?, or does anyone have a better suggestion for me. Also, I have a fairly big slot-ported box that I was planning on sticking the sub in, but would investing in a sealed box be worth the extra money? Thanks.

You are definitely on the right track! You can wire the voice coils of the Alpine Type-R SWR-1242D dual 4 ohm subwoofer (found here) in parallel and present a 2 ohm load to the amp. So, great choice.

Now, the only reason you would need to get a sealed box is if you want a tight bass response. Ported boxes sound good for Rap, R&B, etc. Sealed boxes sound better for Rock, Metal, etc. HTH!!

Well, I had two Pioneer 10's running off this amp and I loved the way they sounded in a sealed box when I listened to rock, so would I be able to get that tight responsive bass from this one 12, or am I better off to just leave it in the sealed box and settle for the booming bass by listening to only rap and hip hop? I'm the kinda guy who listens to all kinds of music, so I wanna find a happy medium so I can listen to both. What do you think?