I've read some posts about this and wanted to ask in light of our situation. We live in CT and have a swimming season that goes from mid-May to October (at most). We have a 33,000 sf pool and are currently running a Jandy CL580, which is about as large a cartridge filter as we can get. I have gotten used to the cartridge filters, but grew up with a pool that had a DE filter.
I find that the cartridge filters are an incredible pain to deal with when the pool is first opened as they do not trap dead algae very well, and they get dirty very quickly. I have started using skimmer socks, which is a big help, but they get clogged up quickly as well. For me to clean the cartridges, it is a pretty big production, from opening the filter, removing the cartridges, hosing them down and replacing them. I do keep spares on hand, but this is still pretty time-consuming. Plus, a set of spares is not cheap -- about $200. The skimmer socks have made it possible for me to get by with 2-3 cartridge cleanings within the first month of opening, and one more cleaning toward the end of the season.
My understanding is that a DE filter will do a better job of filtering out dead algae. Of course it needs to be backwashed. I am sure DE filters have changed over the years, but I recall cleaning out the fingers and replenishing DE as part of the backwash and cleaning process (it's been over 25 years). It took some time, but it was nowhere near as time-consuming as cleaning the cartridges. Plus, I recall the filter disassembly being much easier with the DE filter than with the cartridge system.
One concern I have with the DE system is that we have a well, and it is pretty easy to tax the pump and "water treatment plant" we have in our basement. Is the water loss with DE backwashing significant, or is it something that can be dealt with by allowing Mother Nature to handle some of the work? After all, when I clean the cartridges, we are taking water out of the pool as well, even if it is only 100 gallons or so. I find myself letting water out of the pool throughout the Spring and Summer as the rains add quite a bit of water.
I believe that our filter is about 20 years old, so I am assuming a replacement is on the horizon. When I consider that a spare set of cartridges is about 20% of the cost of a filter, it seems like a DE system makes more sense for us.