I ended up taking the class last night. Since I was already a MGMAT customer, the cost was $95.
I would say the value of the class depends on whether or not you have already taken the MGMAT 9 class series. I took the 9 class series , and to be honest, this extra course probably is not necessary for those who have. The "Live Online Quest for 750 Sentence Correction" class does introduce a new concept in dissecting "hard" SC questions, but it isn't exactly groundbreaking (find min. elements to make a sentence and look for errors here first).
On the other hand, if you have only reviewed the MGMAT SC
book and have not sat through their SC lecture, I would highly recommend it.
With that said, we are all signing up for a committment that will cost over $100K + opportunity cost of lost wages...so if you are on the fence on this class...just go ahead and take it. The instructors were great, and do an effective job of walking through approaches for very tough SCs.