hardtail vs FS depends on terrain and riding style. I ride both, but prefer my FS (Yeti ASR) for 95% of all races I do in New England. I'm at school in Colorado, and I kind of wish I had my hardtail out here, but the FS does fine.
You may find that as you go up in category, you see more people on hardtails. Faster guys generally care less about comfort and more about speed, and many feel that a hardtail makes them faster. I race semi-pro and except on very techinical courses FS's are usually in the minority, whereas back when I raced sport it seemed that everyone was on full suspension. This also has a lot to do with skill level - more skills = less need for FS.
I've done quite a few tests on my hardtail and FS, and even on what may seem to be non-techincal courses I always got better times on the full sus. That was enough to convince me
But anyway, there really isn't an answer to your question. A hardtail will probably be fine for you, not to mention a lot cheaper. But if you can swing for a GOOD, efficient FS then go for it.