Should I buy the M50 MKII?

Assuming you want to upgrade, I'll answer this one. Should you buy a Canon M50 MKII or Canon T8i (850D) camera?

Based on my experience with two Canon M50 MKII cameras and three Canon T7i (800D) cameras that I use on a regular basis I have the following comments:

1) Canon T8i (850D) will have a longer battery life. But for me, that wasn't a concern since I just bought an extra battery for each of my Canon M50 MKII cameras.

2) It will be easier to see out of the Canon T8i (850D) viewfinder since it's an OVF, even if a person increases the brightness of the EVF in the Canon M50 MKII to the maximum level.

3) The Canon M50 MKII with the EF-M lenses is tiny in comparison to the Canon T8i (850D) camera. You may like that or not, depending on what feels comfortable in your hands.

4) The Canon M50 MKII has a sensor that will not let you use the EVF and LCD screen up close at the same time. Note that by saying close I mean really close. For a workaround, I pull my LCD screen out.

5) Until I was able to disable it in the Canon M50 MKII menu, I accidentally would hit something in back that would change my AF to MF. I often would lose an opportunity to capture something. That was annoying. But fortunately, someone on this forum described to me how I could get rid of that.

6) Look for one of those camera comparison sites on the internet to get more detailed information.

It took a while to get used to the Canon M50 MKII mirrorless camera, but by being patience I have to say I like it. For video I found the EVF to be handy for composition. But the video record button on the top right hand side is a little difficult to push on and off. When you push that record button, it's hard to know if it's recording or not other than the tiny red REC seen in the viewfinder. Ideally, if a person had better control of recording on and off of the video using the EVF viewfinder, the video editing wouldn't have to be as much.

On bright sunny days, taking video with the Canon T7i (800D) was more difficult, because we can't use the viewfinder with a DSLR when recording. I would try to see what there was in the LCD screen (but it was difficult) and often I would just guess what I'm taking by pointing the camera in the general direction. Again, that would mostly apply to bright sunny days, with the sunlight shining on the backside of the camera.

With the Canon M50 MKII by using the viewfinder, the video could be more steady. Otherwise without a monopod or tripod or some selfie stick, the video could be "jerky" using a LCD screen with the Canon T7i (800D) camera.

I hope that helps. I'm still learning about the differences and in time may understand things differently. The "M" series may "die", but all of this technology "dies" by being replaced by new technology (just like your Canon SL1 (100D) camera). I wouldn't worry about that. The "M" series or DSLR cameras will be good for several more years, if not as new equipment but at least in the used marketplace.

Oh, one more...when you decide to get a Canon M50 MKII or Canon T8i (850D) camera, you will really appreciate the high ISO photos, all the way up to ISO12800 (depending on the lighting conditions).