Maybe I'm wrong, but I'm guessing that if you manage to move up to Cat 3 with the triple, you'll be fine racing it there.
When the time comes that you want to upgrade the triple ask around if anyone knows of anyone looking to sell some old gear. You might end up finding someone who would be willing to clear up shelf space by loaning, selling cheap or frankly giving equipment to help someone out. It might not be the best, newest or lightest, but you get what you pay for.