In my tests on the R5, the 50/1.8 seems to perform great without IS. Search the forums for "50mm SHOOTOUT" and you'll see that with 10 trials at each shutter speed, the WORST image from 1/2 to 1/15 was sharper than the BEST image at 1/30 or over. It's so good it doesn't even seem possible. Aperture may have played a part in that test, I grant, but the real takeaway is that it shoots quite sharply hand-held at 1/2sec. And not just sometimes, but 10 out of 10 images. Mind = blown! I know they often will CLAIM "5 stops improvement" but I always assume that's in unachievable situations, or very specific lens choice, etc. etc. This is real.
I understand the users of the RF mount without IBIS (which apparently includes the video-focused models) would really appreciate it, but my assumption is that a lens without IS should invariably be simpler, cheaper, smaller, sharper, and have fewer aberrations than one with IS.
