I am in Norway, getting ready to launch Milvina for the season. I went to check the sea water pump impeller.
The pump is Beta's own design, and has been used one season, 310 hours.

The vanes are permanently squashed one side, (we were laid up 7 months) so I will definitely replace it.
I have one spare from Beta, and also a Jabsco one (part 1210-0001) which I bought based on it being dimensionally identical to the Beta. The Jabsco has slightly thinner and more flexible vanes.

Any comments on which one to use?

The impeller seems to have been molded for Beta. I am inclined to think that Jabsco may know more about such rubbers than Beta. Any opinions?