I remember a miglia being set up at Mbe when i was there one day. It had an electric conversion, but i am pretty sure the owner had it set up to turn off above a set speed. Best of both worlds. All depends really on wheel and tyre set up, camber ect ect as to if its really needed. And of course personal preference.
I doubt it was a Mig, I don't think it's alowable in the regs. also, although Migs run large amounts of caster, they have an open diff, so steering effort is not massive.
Was the car blue by any chance? I know a mig-a-like hillclimb car that used MBE, and that had power steering. as it happens I thought about fitting it when I put an LSD in my hillclimb car. but the weight and power disadvantage outweighed any performance advantage. In the end I fitted a couple of UJs to the column to make the steering wheel in a more normal position so my weedy arms could get some leverage on it.