No never compare the penetration of different games by percents. If I had to choose between a 4D game with 1 deck cut and an 8D game with 1 deck cut, obviously I'd choose the S17 over the H17, but bigger considerations would be crowding, speed of game, heat. In a place like AC there is no benefit for a player with a small BR to sit down at the shuffle and start placing bets on -EV hands, so what a guy like you should be looking for are games that you can slip in and out of as you backcount. That way you won't be fretting about finding $5 and $10 limits, you can stalk a pit of $25 tables with empty spots and live a little when you get your count.
While 4D is going to be better than 6D which will be better than 8D mathematically, given the actual logistics of getting in and out of shoes, waiting for shuffles, moving around a casino, there isn't going to be much of a difference in a real session. What you give up in an 8D game will be made up for by being able to play 3-4 decks of the shoe with an advantage without having to get up and run around the casino to find another good count. Most of the disadvantages of 8D come from the additional -EV hands at the beginning of the shoe, but if you're not playing them it's not your problem. In short, you can convert any 8D shoe to a 4D game just by standing there and watching them deal out 4 decks.