Spire and Pulse RDR work fine with re-balls. Never had a jam.
However, my Pulse RDR puts too much pressure on the ball stack with causes paint to break in the breach. Whack a Rotor / Spire on, all is good.
No way to adjust the stack tension in the menu - no instruction manual in the box or online - awaiting their support team to get back to me about fixing this as it is shocking at present.
Tried 4 or 5 brands of paint (GI Winter paint works better, but still 3 breach breaks out of 100ish balls) - FS, various Valken brands, Pure Ice etc
Also, some people are getting speed feeds included with their hoppers (as in, in the box - not as a promotion)... one guy had his delivered with no battery door.