I've had an XP3 running for about 6 months. No problems at all. I have the foam pads that they provide in the bottom basket, a box of bio things in the middle basket (look like sprockets), and a fine polishing pad in the top basket. Works great for me. I rinse the bottom foam and top polishing pad once a month with tank water...no deteriation noted at all. I don't rinse the bio stuff in the middle basket. The fine polishing pad in the top basket seems to need to be replaced about every 2-3 months...it gets pretty nasty, and doesn't rinse clean after 2-3 months.
I do keep an extra pad that fits the filter in my other tank in the middle basket with the bio media in case I ever need to completely clean my other tank filter.