Just a brief and lightweight note for others:-
My migration from 15.6 to Leap 16.0 was quite bumpy and took much longer than I planned. Having achieved this there were still quite a few issues and a learning curve. In summary I found Leap 16.0 less user friendly than TW which I run on a couple of machines. I decided therefore to try Slowroll as being the best compromise, avoiding the pain of the upgrade every couple of years and the hassle of occasional but time consuming fixes.
The migration was easy, possibly because I had learned a bit more about using the migration tool, and the results have been excellent.
Having run Slowroll for over a month I have been so pleased by Slowroll I am contemplating moving my TW machines to Slowroll. The recent large update went without a hitch and I have a system timer set for weekly updates. SEL gave me some learning problems at first but for me it has been great. I congratulate the developer for his efforts for which he has my grateful thanks. Just in case others are pondering a change.