I had an XP3, but the slight--yes slight buzz still drove me nuts. Underneath a stand it seemed to become amplified even more (wierd, but that was the sense I felt).
Pros: quick disconnect, hoses were fine, spraybar was fine, power was great for the cost (no big issues with clogging).
Cons: I classify it as noisy COMPARED to an Eheim 2213 or 2224 or 2026. Water leaking out of the motorhead at the junction of where the powercord enters/exits the unit--replaced original and second one did the same thing. I thought it was a hazard so...
scrapped it and got an Eheim 2213...dead silent and haven't looked back since. All three Eheims I have/had never leaked where it wasn't supposed to.
The XP3 is good for the cost...and like ringram mentioned, its like comparing a BMW with a Ford Escort.
40g AGA Breeder: Pimp# 44: Eheim 2026; Anti- Filstar; CLTT UV; 3 wpg PC, pressurized CO2. GATA! FTD!!!