Arctic has a few other options: http://www.arctic.ac/en/p/cooling/vga.html
Oddly the frontpage shows the PRO as 5870 compatible on the front page, but neither the PRO nor PLUS list it in the detailed compatibility lists.
They have a 3-fan 'Arctic EXTREME 5870' which appears to be tailored to your card, with 250W heat dissipation. Unfortunately the fan-cooler-card sandwich appears to make the card 3 slots thick.
You can probably improve the performance with a a better 92mm fan - the ones included on the PRO/PLUS are only 27CFM. I'm sure they're quiet, but an eg. 40CFM fan wouldn't be too terribly loud and might increase that heat dissipation by ~30-40W or so. As far as I can tell the PRO/PLUS appear to be the same damn thing, I can't see where the 20W difference between them lies.