Wouldn't put Funkmasters in the JF bracket...or the 'good' one, for that matter...just my opinion, of course.
Jazz-Funk seemed like a great new angle for the scene back then, when seeing Level 42 in Brighton as we did before they had the hits really was exciting, would you believe. I don't blame the likes of Donald Byrd for cashing in. I mean, he probably made more in two years than he had in his whole 60s career, but so much of it sounds lame to these ears now they've heard Blue Note gems and all that jazz (which they hadn't at the time).
For me Herbie Hancock's 'Headhunters', 'Thrust' and 'Man-Child' really stand out, along with the Mwandishi band stuff, as exemplary 'jazz-funk' before the genre became classified (or a dancefloor phenomenon over here, at least).
The problem most of the time is that in the fusion the power of both is diminished - not funky enough, or jazzy enough. A lot of old jazz players came out to milk that cash cow and churn out supper club 'funk' for easy money.
Later, Defunkt blew the Pop stuff away. That was some serious shit.