You definitely get more intensity from T5HO versus PC, but with such a small tank like you're talking about, I'm not sure it's really worth the extra money. Your tank isn't that deep, so you don't really need the extra intensity to reach the depths of your tank.
It really depends on what you want to keep. If you don't want any limitations, then T5HO is the better option. But if you just want LPS, and some low/mid lighting SPS, PC can work just fine for you. It may be inferior, but it's still good enough to have a nice little reef.
The other thing going for T5HO fixtures over PC, is that you can pack more lights in the same amount of space. So for a given fixture size, you can get more light output just from the fact that you get more bulbs.
Not sure what the changeout schedule is for T5HO, but I think DarkAnvil is right about PCs needing to be changed out more often. I run PCs and change mine out every 6 months. I think the recommendation is 6-8 months. I can definitely see a difference after 6 months between old and new bulbs. Definite shift in color and intensity.