I have one batch ready to bottle at this point from a two stage ferment with Nottingham followed by K1-V1116. A good mead but not a terribly successful experiment. I figured an ale yeast would kick out some nice fruity esters until it pooped out at ~10%, which it did. I added the K1 after to dry out the last 5%, which it also did. But now it tastes like a mead made with just K1.
I'm thinking that the K1, as a "killer" yeast may have cleaned up the esters, much like lager yeasts clean up diacetyl at warmer temps in preparation for hibernation. I know a lot of mixed culture ferments, like kombucha and yogurt, the bacteria weave a matrix around yeast cells to keep them in place and potentially slow reproduction. I'm curious if the killer action of yeasts is similar, clinging to foreign bodies and feeding off their waste.
Just theorizing, but if you plan on doing a mixed ferment, just make sure the yeasts play well together. I agree with Medsen about separate ferments and blending, much easier.