My 4000gph just started making noise this week after five years of continous service. It still works fine, but I may replace it this spring and keep my current one as a clean out pump. The only reason I am replacing it is because my pond sits next to our patio and the noise in the skimmer sounds like there is a bunch of angry bees in there.
I only use and recomend Aquascape gear. My father-in-law in now on board after he burned through 2 Lagunas in the past 3 years. He has a 3000gph AquaSurge form Aquascape and it is powerful, quite, very effecient and oil less.
Tsurumi makes burley pumps, but they cost a little more upfront and run about double the wattage as the AquaSurge. They are pretty bullet proof from what I've heard. I don't run them, but know people who do and they like them a lot.