you can use the 35mm base in medium format cameras
This is not correct.
There has been one attempt in history of a company converting 135micron thick triacetate into 120 films and the the product showed severe problems. There were thousands of claims.
No other manufacturer ever did this.
Apart from the problems you will run into this is only possible if you spool the films manually as far as I am informed. 120 spooling machines (for sure ours) will reject this base as the diameter of the film will be out of tolerance. There will be jams in the film guides as well.
Due to the known issues, manual spooling is for us no alternative for a premium line product.

What has been tried more sucesfully is to use the thinner but very stable 100 micron PET for 120 and 35mm film (the other way around).
This leads to problems in perforating unless you adapt your machines specially to it which is costly and you end up with lightpiping in the 35mm films.
We have sold the CHS films this way but we feel that a quality product cannot be sold with such an amount of lightpiping so we would not consider this for a premium line product.
We undertook several research coatings in this field and tried with differend anti halation and backside blocking coatings but the lightpiping was not possible to control.
So we decided to keep 35mm on triacetate.

All larger manufacturers use:

100 micron PET or triacetate for 120 film
135 micron triacetate (greybase or clear) for 35mm film
170 micron PET or triacetate for sheetfilm

As far as Silvermax is concerned I alreday stated in the beginning that we used up old stock materials from Agfa in order to manufacturer this film and this is the reason why it is neither a rollfilm, nor a sheetfilm nor APX 100 which is coated onto greybase.

Fomas R100 btw is made only as a 35mm film out of the same reasons.

Mirko