I have doubles, compacts and triples on my bikes, and I generally prefer the triples. I like the smaller jumps that a triple offers. Some of it ends up being a little bit of overlap, but for me it works better. The extra weight is hardly a factor. I don't ride the Tour nor do I compete for the top Cat 1 spots, so whatever weight difference there is could just as easily be lost from my body (and cheaper too).

That being said, I don't think it's worth it to change on your bike. If you want a triple, just calculate how much changing over from a compact to a triple will cost and apply that to getting a new bike. You can't ever have too many bikes.

Why I enjoy triples:
Big ring = Downhills, flats, drafting behind others, etc.
Middle ring = Legs tired, doing rollers, going uphill, etc.
Small ring = Legs are cooked,doing some serious climbing, riding with the wife and kids and don't want to leave them in the dust, etc.