Last question for now I promise 
Do/ can we have a real Feedhold? For example: I send a kill command from control program, it is smart enough to not buffer the command on its end and send it directly. But can Smoothie get such a command, know to react on it immediately, and perform a halt while maintaining position?
I think this is the last big gripe people have. The Kill button results in a position loss, and I’ve talked to a few people that wired a button configured with the pause switch, but that seems very sketchy to me. Any thoughts appreciated.
We don’t have anything perfect there atm, and there is some thinking going on on implementing something better, but it’s going to be a while I think.
Kill will attempt to maintain position, it is just not guaranteed. We have grbl feedhold command, however it is not instant. It would be very very hard to make it instant. not sure it will happen anytime soon. although I would like a real feedhold like grbl has.