I have an Attwood 1250 in the boat, ordered a new one when it started making a funny noise months and months ago and then I found out it was just a bit of kelp in it
now it really is making a funny noise (last 3/4 months) but I haven't bothered to change it until it does actually go pop, it only makes the noise when it is running dry and I think that was what damaged it as I accidentally left it on for about an hour running dry when I was out one day
can't really blame the pump for that!
It has been in the boat since I bought it (March 06) and was far from looking new when I got the boat so I would guess it is a few years old.
Apart from the fact I could just pop it onto the existing base plate one of the things I liked was that the Attwood only draws 2.6 amps while I seem to remember most of the others I looked at were more like 4 amps for the same size pump. It's a manual pump not an auto though, and was about £35 IIRC.