I don't have direct experience with the T50RP, but the T60RP has a lot more upper mid reach than the 58x (heck it has more then the 600 to my ear). In addition to vocals and guitar, you have a lot of fine drummers on that list, the texture of their high hat hits will be less prominent, the guitar plucks less present on the 58x compared to the T50.
While it's true that the T50 signature is more analytical than the Senns, the flipside of the Senn's intimate, lovely mid focus is that they can feel claustrophobic at times, and are a bit genre dependent. If you're concerned about treble and fatigue, Senns are ideal, otherwise I think your first instinct is good.
Planar mags also scale linearly with power, so it's a great can to start with and build up a rig with. . .