The cycle effect on Nourish isn't all that clear. Honestly when I use it I'm multi-tapping anyway most of the time, I'd really rather it just automatically give a new buff type or refresh the lowest duration, depending on enemies in the gut.
I'd like to see Regurgitate reset the energy ramp-up on Feast as well, I love this ability but right now carrying stuff around to munch on is just much more effective. That would give some incentive to a devour/spit/shoot loop while still letting Grendel run around with the things he wants to do. (Eat everything)
Otherwise I'm having a blast with Grendel. Up there with Gauss for my favorite warframes.