I'm quite familiar with Scotchfil putty, and it is certainly worth having on the truck - along with the Scotchkote. Slightly different uses.
The putty / self-fusing tape / electrical tape wrap is wonderful for wrapping Kearneys, split-bolts, PGC's, and the like. I might still use a bit of the Scotchkote to make sure the final layer of tape stays put while the 'filling' sets up. There's a connection that's not coming apart anytime soon. For those who've simply wrapping those sorts of connectors with miles of tape .... try it the "Union" way and you'll be a believer. The task becomes a pleasure. A little bit of putty for the big gaps, a wrap or two of the linerless tape, than a final wrap of Scotch 88. Presto! You're done.
For my work in sump pits, though, I want a connection that I can readily take apart and re-assemble. After all, it's fairly routine to need to replace a float switch. (If you're wondering why I don't make the splice in a junction box, well, I envy you your innocence. Those pits can be NASTY). You can't always be cutting the wires back, or you'll soon run out of wire. You need to disconnect, test, replace, and re-assemble. Then you need the connection to be absolutely waterproof nearly instantly - not 3-5 days later, when the putty cures. As soon as you leave, that splice is getting submerged. Scotchkote is one of the few things that works.
Epoxy packs are good, but you're back to cutting the wires. For the power cables, there are some very nice splice kits that use "shrink tube from hades," and those work very well.
Yet, there's nothing to compare to the Scotchkote method when working on a lawn sprinkler system or farm irrigation pivot. Your wires tend to be small (#20), and the junction boxes / hand holes don't really have room for the fancy grease-filled nuts.
Now ... what would I do if I could not get Scotchkote? (Warning: "Outside-the-box" thinking ahead!)
Well, I might try PVC cement, and see if that works. I might get a spray can of shellac and try that (Shellac drys real fast). Liquid electrical tape- thinned out a bit with MEK. I'd certainly use the epoxy baggies more. I might even try stuffing normal wire nuts with silicone grease. More 'butt splices' and shrink tubing.
I'd also be sure to pick some Scotchkote up while on vacation.