I can't speak for th Teknetics Delta 4000 but the F2 is a great starter machine. Comparable to the Ace 250 but with VDI. One issue I've discovered: the F2 does not like wet ground. The wet sand area at the beach, ground areas right after a rain, etc will make that machine chatter and the static is annoying. Nothing I've tried seems to help. It doesn't seem to effect the way the machine works but it is hard on the ears.