Could be yes - although I seem to think with my transfer from one Samsung to another it brought the files and settings over. Can’t remember for sure now as was over a year ago, but I did not recall any major issue.

Well I use Element for Matrix as well… but why not 10? You only really manage them once when set-up. After that, you just respond to whoever messages you, or you compose a message of whichever one. They no longer chew battery or data in the background. I have 11 installed and there is really no “extra” effort.