Comparing lights is more complicated than just looking at the wattages. It depends a lot on the bulb itself, what it puts out vs the spectrum your plants/critters needs, the reflector, etc.
I am assuming that you are interested in FW plants (since you are reading the Barr report). .... so the comment regarding the actinics don't really apply <Actinics are useless for plants> ...
To properly compare amount of light suitable for plants, you really need to do a spectral analysis of your fixture & lamps. You can find some data on the net ... look for something like PAR output.
A PC is essentially a T5 bent in half. The HO designation is simply to differentiate the older lower wattage T5 from the newer ones - nothing magical in the name. If you compare a T5 & PC of the same wattage, there is no inherent reason why one is better than the other. It all depends on the construction of the lamp, the phosphors used ... etc. as to which lamp puts out more light that is usable by the plants.
Having said that, it is generally true that because the T5 is linear, it is possible to make a better reflector for the T5 so you get more of the light into the tank. The best ones are T5HO's with individual highly polished reflectors for each lamp. It comes down to construction again ... a good PC reflector will beat a crappy T5 reflector ....
Personally, I wouldn't be switching from PC to T5HO just for the sake of the switch.
