Thanks for the confirmation.
(I was suspecting this but was unable to test more precisely to note the difference)
Also, while my eyes can see the “hotspot” and “corona”, I can’t seem to get that image taken with the camera, even when adjusting settings manually (I’m no expert in camera adjustment settings though, so maybe there are settings that can allow a camera to take a better picture of the hotspot/corona thing…
I wonder if this could be done for the S2+ too. Here are some images I pulled from someone’s AliExpress review:
First is stock:
With adjusted reflector:
Apparently he shimmed the reflector gasket with tape:
Ideally you want to reduce the corona for better throw and the 2nd photo looks larger. It certainly made the hotspot look nicer, but who knows whether it was correctly centered to begin with.
Easy way to try is to unscrew the pill a little at a time and see what happens
You were right about the S2+, the stock gasket is far too thin. I added 0.5mm and it looks way better, mine is too thick so tuning is needed.
I tried 3D printing a centering ring for my L21B NM1 since the original one was a bit loose around the LED and was constantly losing its centering.
I admit it’s not the cleanest. On the one hand using a circular hole for the LED might be better to avoid torquing the emitter while tightening the bezel, but on the other hand the square hole seems easier to center if the dimensions aren’t perfect.
I used 1.2mm like above for the gasket thickness. Unfortunately I didn’t do before/after measurements, but the corona looks nicer and it was much easier to center when reassembling, compared to the original gasket. Hopefully it holds up to the heat of the LED, it’s only PLA plastic so it may not be ideal.
By the way, did you ever get around to tuning the gasket thickness for the S2+? Does a thicker gasket improve the throw?
You should get a decent bump in range at 1.2mm. I never bothered to try any further tuning of the S2+ , I had no reason to since I doubt Simon would bother and I don’t have an S2+ of my own, they’re all for sale and I certainly don’t want to make a custom gasket for those, takes too much work without a 3D printer 
In the L21B the increased gasket thickness makes the screws useless, so I always remove them to make it easy to center the LED. Without the screws it centers itself most of the time
Convoy L7
Convoy L6 FC40
Convoy 4×18a
Convoy 3×21a
Convoy L21A – L21B – L21C
Convoy C8+ Osram
Convoy L21C ?
I was wondering about that, too. I can only find 2 references to it, that post you quoted and this: convoy m21a vs l21c - Album on Imgur
My guess is that it’s a typo or mistake in both cases but I’m prepared to be wrong.
If you look at the very last photo it shows the M21A and L21A
that must be a typo, that’s an M21A and L21A in the link