My hams have improved since changing also. I never saw my robo, he was always asleep and my Syrian wasn't very active either. Since the change my Robo is out a lot more and my Syrian has gained some weight too
I suppliment with stuff like the occasional mealworm, mixed puffs, fruit/veg and an occasional monkey nut plus a load of other stuff. One of the reasons I switched is I can't afford the daily essentials supplement for three cages as I was having to supplement my mice's RR diet with the stuff too so they're now on a different mix.
For variety, combining commercial mixes seems to be the way to go, a lot of us are doing it now
If you're stuck for what to feed your mice, I can tell you what I'm using if you want. I'm combining 4 different mixes at the moment for them and supplementing with mealworms, egg biscuit and a few other things and they're doing great on it.