I did commute for a short while on on of the last training bikes I had. Mudgaurds fitted, fatter tryes (25-28c), pressures a bit lower, more relaxed position (bars up a touch), a 15km jaunt, never had a problem - I'm able to easily bunny hop potholes - but a good blast with a steam cleaner once a week followed by a rub over and lube of all the important bits worked fine. Groupset was Shimano, never a problem, wheels 28 spoke stayed OK. In short, go for it, but if I had to go out and buy a commuter, a hybrid or (cheap) cross bike would be first choice.
One other thing, don't try to go as "fast as possible" all the time, learn to relax and enjoy a bit, in 8 miles you hardly get warmed up anyway!