Mac and Api limitations are wholly XE's doing. XE limit each mac address to only one playlist, and it's impossible to use Api without a username & password (which XE don't provide).
But both can be ignored if Formuler can get catch-up working on m3u. Catch-up & the ability to record one channel and watch another is what we need.
I'd say catch-up is the most pressing, as a good catch-up service will drastically reduce the need for recording.