And the answer is, the ore support command ship cannot mine faster.
The base numbers:
Hulk, on Exhumer IV = 30.8 m3/sec. Just on its own.
Skiff, on Exhumer IV = 22 + (5 x T2 mining drones @ 1.1) = 27.5 m3/sec
Mackinaw, on Exhumer IV = 20.8 + (5 x T2 mining drones @ 1.1) = 26.3 m3/sec
Orca, on Industrial Command V = 27.3 m3/sec (using ‘augmented’ drones that will cost 250 M)
Then add Orca boost - as you insist - and the exhumers in fleet will always beat a command ship. And beat it by quite a lot. Note that command bursts do work on the orca but do not work on mining drones. So, the orca still gets shield bonuses but does not get mining bonuses, as it does not use lasers.
Note too that having an ice mining rig on exhumers does not reduce their ore mining yield. And on ice, an orca cannot get near any of the exhumers. At least in principle. (In practice, you would not actually fit exhumers for maximum ice yield as they would be too easy to gank.)
Bottom line, as a solo player, I will use exhumer over orca because it is more versatile for both ore AND ice. As a solo player I will also use orca over exhumer, because it is at least as good on ore and has a vastly bigger cargo hold. And if I can get into a fleet, I will absolutely use exhumer as the fleet bonus does nothing for orca mining yield.