Vinyl and Linoleum Flooring - Marmoleum install over slab AND wood?

I would appreciate opinions on the suggested approach to this flooring installation.

Basics: This is an apartment in an urban building. There are basic older (but not asbestos) black and white vinyl tiles in a small open kitchen, which is off the living room. The kitchen floor under the vinyl is solid cement. The living room floor is 3/4-inch hardwood laid on 1x3 sleepers, which are on slab.

The Problem: We want to replace the vinyl tiles with sheet marmoleum. But we also want to extend the coverage a few feet past the current kitchen area, so the marmoleum installation will have to go over both the solid cement area (current kitchen) and the area that is hardwood, sleeper, and slab (part of the living room).

The installer wants to lay 1/2-inch plywood on top of the current floor for the whole thing, put a skim coat on the plywood, and install the marmoleum on that. Quarter-round reducer strips would be used.

What do you think of this approach?

Thanks very much for your advice.

Either that or use the Marmoleum floating click system. If you know you want sheet goods i would lay a subfloor as suggested.