I can typically keep up decently well on Rhino if I abuse the acrobatics (or if I were to helicopterdash around, but then I couldn't gramchargekill the world).
If I were to do speedruns on bosses (which I probably won't, since I'm more of a completionist-type player) then I'd use a different frame. :V
I'll note that having a Rhino makes bossfights like the Jackal so much faster/easier, though. Maybe I'll try a Rhino speedrun on Jackal later today and see how quickly I can do it.