Not being a light expert or anything, but...
I think it depends on the quality of your actinic lights. There are numerous threads on here about the true actinic 03 bulbs, and how they are focused in the spectrum around 420nm. Also, unlike standard "actinic" bulbs, they are not just white bulbs painted blue, rather they are true actinics. I run PC = 2x65watt actinic 03, with 2x65watt 10k. Since changing to the actinic 03 i have seen a noticable improvement in my corals.
I would disagree that there is no benefit to actinics. The benefit may be lessened becasue of the other lighting Greg is running, 9ie - halides as opposed to PC) but I think it would still help.
Personally, I think adding actinic 03 bulbs would be a great idea...but then again, i don't have halides, so what do I know!
Stewart