Hi Ed,
first of all, we hope not that you end your subscription 
…
… but in case of the case here are our answers to your question:
No, normally not but … … The point at the moment is, that nearly on every update till now, ASOBO/MS had changed anything internally which can lead to negative effects, not working mods or also to CTDs. You see this nearly on every update, that the FBW, WorkingTitle, some sceneries must be updated.
The positive one is, that the main data structure for the navdata are stable since a few updates but we don´t know what happened in the future. So, it´s also not clear for us, what are the update brings - we also see the release-notes when the update is released and we also can test our data than - not before. So, there is no clear answer. Pesonally, I have never cleared the community-folder till now …
Yes - good strategy - move the “navigraph-navdata” folder somewhere outside, make the update and move it back. This is no problem for the installer, but again - in the last three updates, there were no change in the navdata-file structure. So, personally - I don´t move it …
A clear - “not supported” - you can do this but we don´t recommend it. The sim is so new and has so many limitations/bugs/unknown CTDs/freezes/… that every part which is out of the “norm” what ASOBO recommend makes the support harder. I know that such “addon-linker”, creates symbolic links which the OS recognizes as real-files on the real-location but again, we don´t know what on privileges the sim needs exactly and where, what the sim checks during the startup and soon. There are currently so many “if when” that we can´t supported such tools at this stage of the sim.
Further, our updater will be always install in the community folder and we can only to guarantee that the installer works as expected when the data are really there. By the way, that is the same answer what ASOBO will give you. Possible ASOBO will release the usage of such tools some a days but till that is happened, we follow (and we must follow) the instructions from ASOBO to avoid possible additional issues or side effects, which we can´t be handle. Hope you understand what I want to say … I don´t say, you may not use it, but we don´t recommend it nor we can´t give you support when you use it.
Hope that helps to bring a light in your tunnel When not, Ed please ask again - we are here, and we try to help where we can, but we must also follow rules and we also expect that these rules will be followed by our customer.
Thank you very much,
Richard