Actually, I did this exact thing about three years ago. I was tired of hitting my 18 degree hybrid as far as my 15 degree three wood. One night after a very frustrating three-wood performance I went on eBay and found an old Nickent 14 degree hybrid and have been using that as my "3 wood" ever since.
All that being said, I am currently in the market for a new (traditional) 3 wood. The 14 degree hybrid worked excellent for the problems I was having with my old 3 wood (too high ball flight, too much ballspin). However, the hybrid has its drawbacks as well: nearly impossible to get any kind of height on shots, little to no shot shaping ability.
So, I guess I say all this to say that using a hybrid to replace your 3 wood may very well be what you are looking for. I have loved my 14 degree for almost 3 years now. But, at the end of the day the correctly fitted and selected 3 wood will ALWAYS work out better than a hybrid.
Hybrids are hybrids and 3 woods are 3 woods...... if you get what Im saying.