Going backwards, I can see how a U-Foes with slightly less visual flair than their 616 counterparts could work, and would be much cooler than generic Gamma monsters. As is, they're all kinda CGI characters, and that would have to be toned down to make them affordable. But it's actually quite doable, if you spin it right. They would also make more interesting/compelling "Gamma Monsters" than Leader's usual fare, though you'd be changing their origin significantly by having them revolve around Hulk rather than the FF.
I think it'd be interesting to invert things from Hulk bashing Gamma Monsters to Banner feeling sorry for these people that got experimented on before Leader perfected his process. Inverting expectations would have to be the watchword for this film. You'd want everyone coming out the theatre to say "It is nothing like what I thought it would be, it's so much better than those other two!"
But yeah, I'm thinking Leader as our Alexander Pierce, The U-Foes as our STRIKE/Project Insight team with Vector/Utrect as the Winter Soldier, so to speak in terms of leading the bad guy enforcers. Rulk would be our Batroc while Ross would become our Nick Fury, of sorts in terms of having major tension with the hero, but helping anyway because he has a personal relationship with the bad guy, Leader.
I think Jennifer could actually do well as a 'scared of Hulk' companion which makes her transformation into one all the more interesting. While Nat's resolution was along the lines of 'we could use a little worse,' Jenn's resolution is more along the lines of 'I love being hyperemotional.' I think it'd be interesting if Hawkeye got to the point where he was terrified of Hulk, if those tranqs didn't work one time and he ended up getting Hulk's ire. So in a way, Hawkeye would start out as the Falcon-like sidekick and end up having to go his own way like Widow in the end because of who Hulk is. Jennifer on the other hand, would start out like Widow as someone with constant tension with Banner, but in the end becomes a Falcon-like lover of all things Hulk.
I think that could be interesting, but I think they're already covering that kind of Hulk-attacks-Banners-buddies with Hulk fighting a Hulkbuster in AoU.