I don't believe anyone has attempted to figure out remission rates on SLGS. It was in use before TR and it was pretty much trial and error since it was what the people here just "did." There are any number of cats who have gone into remission. The reason we know more about remission rates with TR is because the data were published in a veterinary journal.
FWIW, everyone is afraid of their kitty having a symptomatic hypoglycemic event. However, the fact that you test, learn how your cat responds to insulin, get a feel for what happens when numbers run low, etc. gives you a set of powerful tools. You'll also bet experienced at what to do when numbers are low so you don't freak out. One of the nicest complements that someone paid me was that when Gabby's numbers plummeted (and this happened with regularity as you can see from her spreadsheet), all I did was post her numbers in her subject line and proceeded to do what it was I needed to do to get her numbers back up. Of course, she gave me a lot of experience doing this (and it didn't hurt that I wrote the instructions on how to handle low numbers). My point is that you get to know your cat and how to respond. It's not an overnight process, though.