To give a little more detail on the original question, because the pack is composed of the cards from 6 decks, the 4 decks you end up playing against could end up having all the 4, 5 and 6's from the full 6 decks. Now this would be very very bad for you. The same could happen the other way, with you getting all the high cards, but how are you going to know when this happens? Only getting to see more of the cards will give you more information and hence a beter game. If you could ensure that you had a 4 deck section composed of 4 complete decks, this would be a valid strategy, but as far as i'm aware that's not possible.
If you think about it, there wouldn't be much point to the casinos using multiple decks if they could be beaten that easily.
As to shuffle tracking Bo's completely right. That does solve the penetration problem, but you have to be VERY accurate. If you are more than a few cards out you can kiss goodbye to your advantage (even if you only missed one or two of your high cards, you'll end up overbetting which will destroy you bankroll). That said i wouldn't discourage you.
RJT.