Watching Hugh Brownstone last night who's clearly a big fan of the 50-1.8 S. From first impressions, this lens is an absolute beast (in a good way). Some folk seem to complain about its price - sure it ain't cheap, and of course people like to see '1.4' for this kind of money but 2/3rds of a stop difference (or thereabouts) is hardly a yawning chasm.
I need a new computer though, I'm convinced my poor old iMac was putting up the white flag just now. It doesn't seem to like 45MP files very much.
I think the problem with the 50/1.8 S is that people (including myself) I initially viewed it as the Z version of the 50/1.8 G (which is available new for around £200). As such, it looked like an over priced and over sized lens. However, as you rightly say, it's more comparable to Sony's 55/1.8, which is priced higher. Given its performance (which is better than the Sony), it's a bargain. I picked mine up used (and mint) from Wex for £330
Yes - that's one downside. The files are large and need some computing muscle to process!
Lefty