Yes they do, focusing is easier, and yet, I'd rather use my 24 TSE on a DSLR since I still prefer a mirror-based viewfinder.
But this is purely a matter of personal and subjective preferences. As to a possibly better design, due to the tilt-shift mechanism which increases the distance to the sensor, I doubt mirrorless will offer any advantages. There is a minimum distance to be respected to permit the optical group to move.
The advantage of mirrorless is that it allows the rear optical element to be placed closer to the sensor plane. Tilt-shifts need more room to manipulate the tilt and shift mechanisms, so I'm not sure if a mirrorless design can benefit from the entire offset difference.