My local casino has S17 standup blackjack tables where you can double down on your hand at any time whether it's the 3rd, 4th, 5th, ect. card. However, it only pays 6:5 for blackjacks. Is doubling down at any time really that much of an advantage that it would compensate a 6:5 blackjack payout? Anyone ever play a table with these types of rules?