Here are the rules of the game (8 deck shoe), can you please breakdown the percent advantage/loss:
If aces are split, only 1 card can be dealt to each one:
You can double down after split, except aces:
No resplits:
If double down, and then the dealer eventually gets Blackjack, the double down bet gets refunded back to you:
Surrender is available unless the dealer upcard is an ace:
Keep in mind, that the dealer only deals himself one card, so he cannot check for blackjack after dealing, but you do have the option to surrender based on that one card before hitting your hand unless it is an ace, in which case he MAY get a blackjack when it's his turn.
Double down on any cards (Including aces, unles you split the aces):