Yes, the Steelsring adaptor gives you control of aperture.
Regards
Fraktal
Yes, the steelsring allows aperture control.
But the opening of the adapter is quite narrow (look at the product photos, you will see). I checked this with a friend who has the steelsring. There is vignetting from the adapter even with just a few mm of shift. If you can live with the restrictions of fixed aperture - a dumb adapter with a wider opening is a better option in my opinion.
I use the PC-E 19 on the GFX 100 with a combination of:
1. a very thin and precise Novoflex Nikon to Canon adapter and
2. the HCam Dual Rotation Shifter.
Aperture is preset to f13 in my case. Focus peaking can be used to check focus across the field but I usually work without focus peaking - and never missed focus yet.
The Cambo solution looks great too, but I am not a fan of this setup. So I am very happy with my solution which gives me best possible ultrawide quality for architecture. The image quality of the PC-E 19 is indeed great and much better than the TS-E 17mm.