Great shafts for the money...heck, just plain great shafts.
I just recently set up some of the 300`s for my Predator.
A bit of fine sandpaper and a proper cleaning, and the Platinum Fletch tite has my feathers bonded as well as any other I have had. Plenty straight, and I have yet to break one even though I have been abusing them...(my old Carbonwoods have me spoiled with durability)
I would go with the 500`s as I think these shafts run stiff. As usual with carbons, leave them long and cut a little at a time.(1/4" means alot) If they finish too light, weight tubes will take care of it for you.
If you are new to carbons, just keep an open mind and do what you know. Arrow spine is arrow spine, regardless of shaft material. I was resistant to carbons for years and they are now my favorite shaft by far.