Well-written OS3.x/WarpOS (or PowerUP) software is not context switch heavy, so the whole context switch overhead issue ought to be largely irrelavent.
A PPC with OS3.x gives a much needed boost to a lot of computationally intensive operations, such as datatype decoding, image dithering (3.9 picture.datatype), mp3 playback and of course any games written to take advantage of it.
With MOS installed, you get to run your 68K/RTG apps faster than the real 680x0 could manage (especially the 040).
Overall, I'd say, yes, there is a point. Using the second 1200T here that has an 040+mediator, the difference provided by the PPC for the common tasks (datatype stuff) is readily apparent.
