I had a big sand filter that probably just needed a sand change, but I let the repair people talk me into a new DE filter. I regret it. The sand filter was very forgiving if I let it get a little green; the DE filter (even though it's a big one) gets clogged way too quickly.
Water clarity is slightly better, but not nearly enough to justify the extra effort. Wish I had the sand filter back. YMMV, obviously.
Brad