My arse is considerably wider than yours, and SQlabs seem to change their saddle designs with regularity, but with those caveats in mind, here is my 2p
The sqlabs saddles definitely favour a certain type of rider – one who doesn’t move about too much in the saddle. They’re fairly flat saddles, and I think you’ll find them quite comfy in contrast to your Charge (which I also don’t get on with).
I can’t speak for the latest iteration of the 611, but I tested one of them a few years ago (a 611 and a 612 I think) and found them very comfortable, especially on long distance rides. Personally I found them better suited for road than MTB, at the time. If you’re at the chunkier end of the spectrum, weight limits weren’t particularly generous, and I’ve bent a couple of sq labs saddle rails without crashing them (I was at the upper end of the weight recommendations at the time, but I didn’t exceed them). The max weight for the 611 these days I think is 90kg. I can’t find the review on the site though, soz, but I mention the 612 here (which looks very similar to the modern 611 ones)
I’m actually testing the 60x ergowave for this here site at the moment, which I lik – it definitely encourages a slightly more forward seating position than I’m used to. The ‘shelves’ on it, for want of a better term, seem somewhat more pronounced than the ones on the 611 you’re considering, so that might not be as much of an issue. I have absolutely no idea what makes one saddle (this one) ebike suitable and another one (the 611) not, mind you.
The Power comp I only bought recently as a bit of an experiment, and I *really* like it. I think it encourages (or forgives) a little more positional adjustment than the sq labs 60X, but it’s still a relatively flat saddle, in the overall scheme of things. Speccy suggest it’s a road saddle more than a mtb one I think on some of their marketing, but it works really nicely on the mtb. The stubbiness isn’t an issue either, even on longer climbs. The massive hole in the middle it something of an issue on wet days without mudguards though, if you’re adverse to a thoroughly moistened gooch.
Not sure if any of that will help, and everyone’s arses are different, but hey 🙂