My concern is that fusing experiences may lead to loss of individuality. We could fuse all minds into one simple eternal bliss but its is nit far from death.
One solution is fuse which is not destroying personal identity. Here I assume that “personal identity” is a set of observer-moments which mutually recognise each other a same person.
I absolutely agree with You.
My only objection is that SI may value minimalization of suffering more than preserving personal identities from death (I think the same, reincarnation in above interpretation and fusing minds are death of “person”). Such an SI would be in some (maybe even strong) sense promortalist. For now I don’t want to choose what vision seems more probable to me. I don’t think mine is impossible, though for sure is not more preferable.
I also hope there would be possible to fuse minds without destroying their personal identity. Maybe SI would choose to simulate less copies of more diverse minds after fusion rather than greater amount of just one.