I would say that depends on what you're going for.
Personally I think that it matters more what type of approch shot you have than how far you hit the ball. This can vary from person to person and course to course as well. I've played courses before where the rough doesn't really punish you at all but the holes are pretty long (as in 470yd par 4's). In that case, getting "out there" is a pretty big benefit and being a few yards into the rough might not matter. The opposite can apply as well.
You also have to look at your game and determine what really matters, to you. I know quite a few people who'd rather be 160yds out in the rough than 170yds out in the fairway. Why? Basically because their chance of hitting the green, even from the rough, from 160yds is about double that than it would be at 170yds.
I used to work pretty hard to make sure that I was always one of the longest off the tee, even if that meant slipping into the rough a few yards. It was an ego thing. Once I learned to check my ego and work on long, accurate shots (with an emphisis on accurate), I started to hit more fairways. Once on the fairway I could play the type of shot that I wanted to depending on the conditions, hole location, etc. Which resulted in hitting more greens and yeilded shorter puts as well. In the end, I found that my handicap dropped quickly. All because I quit worrying about how far I hit the ball and worried more about putting the ball in the right place.
So... Probably not the kind of answer that you we're looking for but I hope that it was somewhat useful anyway.