I REALLY wanted the 20-40mm but it was a stretch, then I spoke to BigMacCam and Sandy Hancock and they weren't overly complimentary. Sandy described it as a bit ... beige. I think it is excellent compared to other zooms but not compared to other limiteds. As for limiteds, I am currently doing a sic with a 15mm limited that I got for £250 from a used camera dealer (MPB) and it is exceptional. Its the smc so I get the super pointy star bursts. The 40mm cost €160 and is blindingly sharp. I know you have the 35mm so the 40 is probably not that desirable but when you do get one, to complete the set, you won't be disappointed. @Tsuken got a 21mm limited for Christmas and plans to use it all year. He started a thematic thread and roped us all into posting a shot taken with the 21mm on the 21st of each month of 2021. Worth a look before you pull the plug. This is a link to it
21 in 21 - pictures thread - PentaxForums.com
I used my 21mm inside churches both here and in Cadiz and the sharpness, front to back was superb. Every lens has bad copies, and some people don't take the trouble to calibrate a lens before writing it off. Keep that in mind when you read reviews. I tend to listen to people I trust. Vanya knows his stuff, as for me @SandyHancock, @BigMacCam and @Pepperberryfarm are my go to gurus
Re apertures, I know the 21 is f3.2 but hand holding in low light is a breeze because it is the size of a couple of biscuits