The 1200w shite is Peak mate, they only 400w RMS from what I can gather. If the sub is giving 2400w RMS id be surprised, but say its giving 1000w, it will be more than powerful enough for the subs alongside some speakers.
Unless you really push it too far, it should do the job. Its a shame car audio places never give RMS ratings, because PMPO mean jack shit, I guess its because chavs like to think they have 4000w of power in their soundsystem and that is who the sellers appeal to.
You wont stress an amp that big, unless you really really push it up. Thats the idea of it. You may find that you will need a power cap though, if it is 1000w RMS or greater.
Personally, I like to go for higher impedence, 8ohms+, but like I say, car audio is all about boasting big numbers, rather than actually giving loud and crystal clear sound, as it should sound.