Charlie wrote in post #18810916
it's fiddly.
imagine shooting with the 11-22, 24-70 EF and 135 EF. Pretty normal to have said combo, you're shooting the 135, go inside with the 11-22, decide to swap to 24-70, you've got to swap out adapters (135 -> 24-70), then swap lenses..... ugh fiddly. Sure, EF lenses are low cost offerings, however price isnt everything.
I've played these adapter games, still playing them now. Only way to make it comforting is to have multiple adapters, one for each lens. With that, you get into size creep, an additional 250g for two adapters, additional length, and costs...
The booster is an EF adapter and .71x TC all in one, no need to pull it off ever when using EF lenses. If you want to mix EFM lenses, sure I guess so, but either I am running with EF lenses for non travel, or EFM lenses when traveling and wanting to go totally light and travel friendly.
My only point is that the M50 and EOS RP are basically siblings, using different glass, other than the EF lenses bridging between them, and you could just use EF lenses in FF format on the M50 if you really wanted to save costs.