I tried a Heron on two different Gus's
Problem I had and this may be just me, but, without the 510 adapter on the Heron, I found it EXTREMELY easy to over tighten the Gus. There is no "stopping point". First time I did it, I compressed the spring on the Heron, loosening the connecting pin. When I fired it, it shorted out and instantly got too hot to touch. It took me a few minutes to figure out what the problem was, but when I took the switch apart, the spring was compressed out of shape and loose.
Again, this is just my experience that I know of. I'm sure others do it with no problem, but I can't have something that is so specific in battery changes. One small error and you'll hurt yourself. Then again, it may have not even been the problem. But that Heron never did anything remotely close to that on a GP.