Could have been a disaster, could have been great. I think had RTD written it with Judith and Garfield Reeve-Stevens, it would probably have been the latter.
It would have been a logistical nightmare to make though. Two very different shows made not just in two different countries, but in two different continents, one airing on national UK tv and the other a syndicated US show? You'd probably need the Doctor on the production company to make it work.
Still, The Doctor meeting Dr Phlox would have been fun. Sigh.