From my readings and participation in many other boating forums, it seems like all Shurflo pumps,
less the Baitmaster Pro, seem to have be replaced on a annual or every other year basis. A few friends using the Baitmaster combo washdown/livewell pump seem to be satsified and get more than a few years out of them.
In regards to washdown pumps, Powerboat Reports, in their Nov 2004 test, said this:
"If you have the dough ... and need the flow ... get the Groco!" They liked their C60 and C80 pumps which put out 7.5 gal/minutes, but costs $305 & $399 respectively.
PB Reports also
highly rated the Johnson Marine pumps, specifically their Aqua Jet WD 3.4 & 5.0 models. The WD 3.4 model was the only pump in their tests to make or exceed the Mfgr'rs labeling claims for performance. They run $140 to $165 and have a 3-year warranty. Also see this test report on them
here.
Now for actual experience with them, my brother's Grady is an '87 and to date it has only ever had 2 washdown pumps installed, both being the Johnson brand pumps. The
original Johnson P15 model washdown/livewell pump lasted 14 seasons before it needed to be replaced, so he replaced it with the same model. Sadly, that P13 model is now discontinued ... ??
For heavy duty use ... go Groco ... as metal beats plastic! See here.
Hopefully others will chime in, but that's the only info I have to offer.