Well ... after four years into oblivion, the 650 thread is back!!!
I know it can be impractical, that having to carry separate heads, and bit kit, and jigsaw blades, and whatnot can be too much to some BUT, it was one of "my grails". Found it at a good price, and not much work to be done (reposition springs; clean; hone knife; make needlenose pliers head). Came in the mail today and, 2 hours later, this is the result!
Now the quest begins for getting a sheath, fisherman's and cable cutting heads (and might make a replaceable cutters, needlenose head just for laughs)!