Have you thought about getting some software, like CVCX, or Blackjack Risk Manager to compare the different games and conditions? Also, there are some must read books out there with tables and charts which will answer your questions about different conditions, e.g. Blackjack Attack, 3rd Edition. I'll bet you will love them.
However much I dislike computer program, maybe I should just buy and play with it. Maybe it is a wrong approach, but I do prefer actual experienced player giving me their opinion rather than computer or book.
I will play the 6 deck game with 1 deck cut-off before I would play 8 deck. Assuming rules and min table limits are equal of course. You didn't mention anything about shuffling! I will NEVER play at a table with CSM's.