As already posted the slide stop is Kägwerks. I like it a lot after a few days of messing around with it. No fit issues as far as Safariland 7TS, don’t own any other holsters to comment on at the moment. Pictures make it seem awkward but it’s in a really good place and function is exactly what you’d want, out of your way, but easy to reach when you need it. They have plans for Gen 5 and 43 models, they’ll be going on all of my future Glocks.
As far as the Mayhem-Syndicate comp, it’s my only experience with comps in general but I think Mayhem has the best attachment method on the market. This was from their first run what they now call their “cali-comp” but I have their MK2 on order for a Glock 45 I’ll be picking up. I think it works great and was a noticeable difference the first time I shot with it, recoil feels very flat in contrast to no comp, more of a push back than any flip, fit’s all of my 17 holsters, no set screws, etc, a lot of positives with no downsides that I’ve found. They confirmed 43 barrels are coming as well, so I’ll have these on at least 19 43 and 45