I have used t5's before and they work great. However, i have noticed smaller yields and less denser buds. I recomend LST to make up for some of the yield loss. Other than that i dont really see a difference in quality. They smoke just as good with just as much potency. On another note, Since i live in hawaii, its a great way to save on electric. We have ridiculous rates here.
Im currently experimenting with some t8 litro bulbs. my local hydro shop recomended these. I was really skeptical at first, but after seeing some of the stuff they have grown using them ive definitely been excited to try them. check out my grow if your interested.