The Jase3D thumbscrew is a very simple piece. It consists of a hex screw with a 3D printed part screwed on as far as possible.
Jase3D thumbscrews do their job just fine, as does pretty much any other thumbscrew. What I like about the Jase3D ones is that should the need arise for a longer or shorter screw, the 3D printed piece can be easily removed from the old screw, and attached to the new one to make a thumbscrew of the appropriate length. Note that the head is significantly taller than a more generic thumbscrew, such as that of the Worker one, which may pose an issue for sleeker blasters. In contrast, the Jase3D thumbscrew head is also a lot narrower than typical thumbscrews, which works nicely in my situation, but may pose an issue if you can't get a good grip on them. For 3AUD each, Jase3D thumbscrews are a useful and relatively cheap product.
With the flared magwell attached, the Stryfe does become noticeably bulkier, though the piece should present little issue unless you use it as a secondary/sidearm in a tight fitting holster.
The flared magwell is an accessory designed to improve usability, by increasing the tolerances for reloading. With the flared magwell, a mag does not have to be perfectly aligned with the magwell to be inserted, rather so long as it is caught within the flared magwell, it will slide in just fine. With less need to align a fresh mag perfectly, reloads can be performed slightly faster and with a lot less thought and effort, which in turn can improve combat performance. It does take a little getting used to, as initially it does feel very awkward sliding a mag along the inside of the flared magwell, however the advantage in combat can be quite significant, especially when on the move or under fire.
Jase3D offers flared magwells for both the Stryfe and Rapidstrike individually, as the pieces are not cross compatible. They are available for 15AUD each, which I feel is fairly reasonable for such large pieces. If you have no issue with some extra bulk around your Stryfe/RS magwell, and don't use 18/35 drums, a flared magwell may be a purchase to consider for the extra convenience it offers during reloading.
The Jase3D RS pusher cover is unusually expensive at 12AUD, only 3AUD shy of the flywheel motor covers. It's substantially more than any other pusher motor cover, which is often included with the flywheel motor cover, and is even more than a lot of flywheel motor covers. As usual with motor covers though, it all comes down to personal preference. I feel that the Jase3D motor covers are by far the best looking ones out there, whether or not you are willing to shell out the extra money depends on whether you think it's worth it.