Resplitting aces in a six-deck game adds about 0.069% to your bottom line. That extra half-deck of penetration from 4.5 to 5 decks with the rules you describe adds about 23% to your bottom line if you are betting optimally. Panama Rick is right when he says there is no comparison.
Questions like yours are very sensitive on a public forum because any kind of answer might lead to a deterioration of the games. If we say that the resplit is important they will abolish this rule.If we say that pen is important they will cut the shoe in half.So I won't tell you what I think and may be the others were just kidding.
There is now enough BJ-Software on the market by which you can find out by yourself.We don't need to educate the casinos here.
You make a good point, but on this issue, I think the relative values of good penetration and RSA are pretty well known. Of course, for the casinos, there is a cost to short penetration and they have to figure out the correct balance. That's where they seem to fail. What casinos don't seem to realize is that many of the things that are good for counters are also good for them. Not too long ago, I played against a dealer who was lightning fast and who dealt 5 out of 6 decks in a house where 4 to 4.5 decks is the norm. I'd be willing to bet that this dealer makes more money for the house than two of their "normal" dealers put together.