Yes. I have used both for a long time and I honestly don't think T5 is any better, I found that the T8 with a higher kelvin, the light reached the bottom of the tank and my plants grew well. And in the T8 tank i didn't have co2. T5 was far to hot, overpriced and unnecessary IMO. T5 IMO s no better than T8 if you have a good T8 set up. And I would only have T5 with CO2. T8 lighting is great for NON CO2 tanks.
IMO the real question would be what the PAR level is in mmol for the bulbs you have, and maybe comparing a few spectrum plots of various bulbs. If you're really in to things, you could try to roughly assess PUR. If I were to take consensus from the opinions I've read, it would be too much. The physics behind it is more important though; if you can figure that out, you have your answer.