I think there is some confusion here and it is important to realize what the rules are and where possible exceptions may occur. First, as noted, if the contracts are under one master, they function as one contract. That means that using points together is not a transfer but it also means that you only get one transfer (in or out) per UY for the master.
Technically all rules apply to owners of multiple master contracts, however, exceptions are the rule and are handled on a case by case basis. This means that it is often possible to have multiple transfers and even transfer banked or borrowed points at times. There are no guarantees on these exceptions and any flexibility could vanish going forward.
I think it's prudent to assume that the published restrictions (one per, banked/borrowed) will apply to single owners of multiple contracts as if they were different people when planning. My view of the likely exceptions are in 2 situations. When you need enough points in a single contract for a one nights reservation and for the exchange options where
DVC requires the points be in a single contract such as for
DCL, etc. The bottom line to me is that one should only consider an exception as applicable if it's the only way to make happen, what you need to happen to actually make a reservation. This DOES NOT mean, in my view, that one could consider such an exception likely due to the 7 days at a time reservation option.
The banking change took away one of the major benefits of making sure all contracts were under one master. Now, the option of multiple exchanges in or out is a plus for multiple but separate contracts. It's also a potential plus for those looking to rent out points on a larger scale.
In the past such an action often resulted in a change of home resort status. I know that was supposed to be fixed and some have said (words only) that it was fixed, but in function I don't recall a single post that convinced me it was. Now I don't read every post so maybe actual examples have been given and I missed them. We've also had 2 computer upgrades since it was a topic of discussion so it likely has been fixed.
Finally, and most importantly, all of this could change tomorrow including transfers could be eliminated totally. This is an area under total control of DVC. One needs to understand the risks of timeshares to participate.