I have XP3s on several smaller tanks and they've been working great. When the XP4 came out, I jumped on the opportunity to try their 'improved' filter. What a piece of junk. Worst filter I've tried in over 25 years. Their new stronger motor has eaten 3 impellers in less than 6 months. The filter was only enlarged in the vertical aspect and is too narrow to run for any length of time without clogging. I have to shut it down and clean the med and fine pads weekly.
For larger tanks, steer clear of the XP4 like it has herpes.