I really think that allowing subscriptions to both exact whitelists and regex whitelists would be incredibly useful. I've just posted my use cases on another, related issue and would rather not repeat myself verbatim here.
Of course there are risks from using publicly maintained lists from people / companies with agendas (paid to whitelist ads etc), or those lists which are compromised (this exists for exact blacklists too - simply delete the list content), but what about those of us who simply wish to maintain their own lists on Github for personal use who don't want to mess with SSH, Python scripts or slow interfaces every time they want to just add an item (especially when coupled with Group management for 100s of individual rules)?
Please, please consider this. From looking at the system that currently exists (which is amazing!) I don't think that supporting different kinds of lists (in addition to individual items) would be beyond the realms of possibility. You could even put the feature behind an advanced option to prevent 99% of users ever encountering it...