I have one of each.
The normal Speedseal does nothing which the standard cover plate doesn't do, except for the big thumbscrews. It might be flatter since it's a machined piece rather than sheet metal, but that's it.
The Speed Seal Life has a channel machined out for the Teflon washer. Now THAT is cool. This will save the cover plate, if not the impeller. I think the benefit to the impeller may or may not be as great as the makers claim -- my impression is that they fail from friction with the pump body, not with the cover plate. But that doesn't really matter, because the cover plate is protected and friction is reduced. Definitely worthwhile.
I can't say I like the thumb screws much. If you do them up hand tight, they fall out (as happened to me). So you need a tool in any case. I think I'd rather have a normal bolt head
, or allen key. Maybe thumb screws with an allen key socket inside would be the best.