I was thinking, why not use triggers as filament sensors? I have not put any yet, but have you tested?
Will this go into tool change macros?
I use M591 for normal printing with filament sensor outside of tool changing. I only use the triggers during the tool changes so I can show particular messages depending on where in the tool change an error/state occurred
i found something else too unique to me, due to me having a "C" axis the trigger also reported that endstop as well as "B" even though i was configuring it for use while print from SD card
so i had my offending B-axis playing up as described by not conforming to the on the fly M574 commands. originally it was connected to the E2 driver on my duex2. i read on the wiki in regards to M591 not being able to be used on these pins so i thought id see if it affected the endstops too. so i changed A and B around so the B axis is now on the E1 driver on the duet main board and it works as intended!