noob in all these terms.

the 1st grundfos pump has served us far over it's warranty period, we are very satisfied with it.
i think roughly 4+ years, probably 5 or 6 years. can't really tell now.
properly being exposed to heat and rain, it got short-circuited, though we do provide a cover for it to minimize the exposure. can't help with it, as we have to put it at backyard.

when replacing it, due to urgency and tsunami pump seems like providing similar functions and same warranty, but lowered cost, i tried it.
but now really not satisfied with tsunami pump, 1 factor it is practically constantly running, and far louder noise and vibration.

i'm deciding whether to pick the proper sizing CM  3-4 PM1
or CM 3-5 PM2, which cost 200+
according to the brochure
https://www.grundfos.com/products/find-prod....html#brochures
PM2 has extra features

Integrated pressure sensor from Grundfos Direct Sensors™ 
Adjustable start pressure 
Start / stop with 1 bar differential pressure 
Auto restart after dry running 
Max. run time 30 min. (safety) 
Pressure indication 
Internal pressure tank 

but the supplier only has PM2 on 3-5 model, a slightly bigger capacity