I have two Hornby class 73s with the latest motorized bogies - one has traction tyres and the other does not. I assume the wheels with tyres could be replaced if the non-tyred wheels were available as spares, as only a single axle is required. Bit expensive to get a complete set from Ultrascale though.
The Bachmann 4-CEP has the power bogie at one end of the set, and I've experienced no running problems at all when the power car is at the rear of the train. I've even tried it with the power car at the rear with 4 Bachmann MK1s on the front so it's pushing 7 coaches, and again no problems even through curved Peco code 75 pointwork. As to close-coupling with the 4-CEPs, I've dispensed with using the lights because they're not very good anyway. This allows me to use NEM couplings of my choice between the coaches and I've fitted Rocos. These mean the corridors touch on straight track - especially with the power car at the rear.
I was going to purchase a VEP but I've decided against it due to all the issues. My little passengers are benefting from extra CEP comforts instead....