I did the MCC with EPTA on the Tristar, and I think it's the best thing I've had so far! If you are a competent pilot you'll get out of there with a lot of confidence, the guys teaching (especially Cpt. Smith
He's also the guy that has loads of experience on the Tristar as someone said, so he knows exactly how to work the thing) are top blokes and they'll sort you out with multi crew cooperation in no time (if you do put some effort in yourself that is)
We had a group of 4 guys that were all pretty experienced and who knew how to fly, so we didn't really come across any problems. Just do it I'd say, you won't regret it!
(plus like you said, it's pretty cheap compared to others who use the 73 sim, but hey MCC is MCC, you're not doing a type rating, you won't learn how to use EFIS or whatever, you just get a first impression to big jet handling.)
good luck