I went and bought an Cherry MX 3.0 board (g80-3850) just to get the keycaps. Here's some pictures for anyone else who might be interested:
Picture of the keyscaps except for capslock on my tenkeyless. Cherry supposedly use POM on some of their keycaps, so I can't tell if this is ABS or POM. Legends are laser etched on and sticks out a bit from the top of the keycap.
The caps are of course low profile. They differ from other cherry ones in they have an tiny distance around the base which isn't sloped. They also produce an much more subdued sound when typing and bottoming out compared to the OEM profile ABS caps I have. The top area is of same width but ~1.5mm smaller in height compared to that of OEM keycaps.
Of course ignorant designer still haven't bothered to center the stem despite it being perfectly possible.
Profile view shoes that it's pretty much flat, no sculpt I believe.
The original keyboard uses cherry stabs. There's a slight problem with fitting the keyboard onto costar stabs: if the wire is thick then the part of it that goes around the switch will bump into the bottom of the cap. This can be solved by filing/cutting away a part where the wire bumps into the keycap.
You can fit O-rings onto these. They still attach fine even with the 2.5mm ones that I'm using (obtained from LPWL) however it'll leave a gap as seen on bottom part. I'll probably end up getting 1.5mm rings which should work out perfectly for these.