I think that, in general, training with guys like Berto and everyone else who has offered their services is probably a pretty good idea and she could probably even go and spar with Cecilia Braekhus as well, to help her career in the future.
But I don't think that helps her against Holly Holm. I don't think she can close that gap at all. If I were Ronda, my entire game plan would be to get it to the ground. Take her down, even if you have to pull bottom half guard and submit her as soon you possibly can, otherwise, Holly Holm will likely win the fight again.