By all reports I've heard, the Perflex is not a bad filter, but finicky to work on. I think some of the newer filters are easier.

Both filters you are looking at are 'over-sized' for your pool, which is a VERY good thing, and they are roughly equivalent in capacity. Here's some comparison data.

Cartridge => Hayward C7030 725 Square Feet SwimClear Reusable Cartridge Filter @ Amazon
Hayward CX591XRE Replacement Cartridge @ Amazon
Hayward product page

PRO:
+ very little water used to clean
+ very little debris (just dirty water)
+ moderately good filtration.
+ will work with algae in the pool.
+ cycling pump on/off has no effect on filtration

CON
- subject to pleat collapse if the filter is allowed to get dirty (3 psi pressure increase)
- expensive routine replacement cartridges ($250+ for C7030)
- more expensive filter, than equivalent DE filter.
- cleaning is a 'you get FILTHY' process.
- works best with light loads and few swimmers (not much lotion, etc.)


DE => Hayward Pro-Grid Vertical DE7220 DE Filter @ Amazon
Hayward product page


PRO
+ excellent filtration; clears water faster than any other filter.
+ more tolerant of over-pressure (under-cleaning!) than cartridge
+ lower maintenance cost ($50 DE filter powder / year)
+ filter costs less than cartridge system
+ works well with high dirt / high swimmer load, including parties
+ removes bacteria and algae spores from water.

CON
- backwashing discharges dirty water + DE in 200+ gallons of water.
- live algae stops filter up almost instantly.
- multiport valve needed for easy operation.
- annual disassembly and internal cleaning needed.