I have a reasonable road bike + tri bars.....
I now also have a shiney newtri bike
1. Get a bike fit on a tt bike. I thought iknew what iwas doing but i was way off ( luckilly i bought the right size buti hadno real idea of the tt position i shouldbein - its different to a road bike.
2 the tt bike is quick....., very quick, but only when you aredown on the bars
3 but its a bit of a pain in a group ride
4. If you are committed to tri buy a tt, otherwise buy a power meter
5 alterntively, get a coach. Getting fitter will improve your bike, run and swim...... you could get 3 years coaching for the price of a tt bike.