I rarely if ever use the 4 wood off of the fairway, I generally hit my 4 wood in the 205-210 yard range off the tee and my 3 hybrid about 185 off the deck and 190ish off the tee, so it's about a 15-20 yard gap. I've also thought of adding a LW, but my short game is my big downfall right now and I think I should try to improve my play with the GW/SW before adding a LW.
I hit my current hybrid pretty good, for some reason the bigger head of the fairway wood intimidates me off of the fairway or in the rough, which is why I was leaning towards another hybrid. I was trying to fit in a club that will give me +/- 200 yards off the fairway.