Z-4000 and Proto 2 Question

[GPJ68]

I'm giving some contemplation to buying a lightly used MTH Railking loco with Proto 2. I don't have DCS, nor do I ever foresee adding it to my layout (once I rebuild it after the move to SC). What exactly will the Z-4000 control/activate on Proto 2 engines when run conventionally? What am I missing, by not having DCS and running Proto 2 engines off any other (non-Z-4000) transformer?

Frankly, MTH engines have been very, very low on my interest list (because of DCS and the whole Proto 1 battery fiasco), but there are a few out there in Western Maryland livery that I'd jump at for the right price (meaning way cheap).

GPJ