I have hard tops for my cars and really enjoy them. They give the car a totally different look.
As far as track use, they won't give you any real protection. There's not much to them structurally. I use a Brey-Krause rollbar extension on both my hard top cars for a little extra protection.
Roll Bar Extension for 986 Boxster
If you can find a top, grab it. I usually see them in the $800-1500 range.