I have used purigen in a few of my tanks to get rid of cloudy water, though I have never used it in Sw. My guess is most folks just use one or the other, and don't have a ton of experience with both.
I have used both and now only use Chemipure Elite. I know Purigen can be recharged with bleach making it more costs effective but I have had good results with using CPE only and replacing it every 2 months.
Chemi-Pure is carbon + a purigen type material in the bag as well. Not as much as what is in a purigen bag itself, but it does have resins in the bag to absorb stuff just like Purigen.
Personally, I used Purigen for a few years early on but now I only use Chemi-Pure.
Using purigen will probably work better than chemi-pure alone (there is less resin in chemi-pure than what you would use with Purigen, from what I've seen). You could always supplement with carbon and get an added effect. Purigen at least has the added benefit of being regenerable.