That is not totally correct. It's not the insulin that kicks you out of ketosis. Elevating insulin without an increase in blood glucose level will not kick you out of ketosis.
The thing that kicks you out of ketosis is an elevation in blood sugar (when you eat carbs for example) the insulin increase is not what kicks you out of ketosis.
Insulin elevation is associated with getting out of ketosis because under normal situation an elevation in insulin level is caused by an increase in blood sugar.
But if you inject insulin while being in a ketogenic state and without eating carbs it will not kick you out of ketosis. Thus it is not the insulin that will kick you out, it's the elevation of blood glucose that causes the rise in insulin that does.
In fact in hardcore bodybuilding circles insulin injections are used to get in ketosis faster because it drives blood sugar down. I know some pro bodybuilders who can have a huge cheat day and be in ketosis the next day by using insulin a certain way (not a subject I care to discuss or has its place in my forum).
And it works. I've went hypo several times because I had leucine by itself while being on a low carbs diet in the past (live an learn). One occasion was especially scary since it was early and the health bar at the gym was closed.... and it was around the same time as the H1N1 virus, at first I though I had the virus before I realised what was happening!
It IS true. Sucralose doesn't have enough of an effect. In fact normally it doesn't eve lead to a release in insulin except for those who are insulin resistant. There are several studies showing no insulin response to sucralose and other artificial sweeteners.
Some people are more sensitive than others. Some will not notice slight drops in blood sugar. I'm very sensitive to it and I went hypo several times from ingesting leucine too far from other nutrients. Never happened with sucralose even if I used to consume a lot of it.