I've often thought it would be cool if they occasionally came up against an enemy equivalent of the IMF, a recurring foreign team employing the same tactics.
I've had exactly the same thought. The closest they got was 'The Mind Of Stefan Miklos', but actually showing a full-on Iron Curtain IMF - or even breaking series format and showing events from the black hats' point of view as they try (and fail, obviously) to bring down the IMF - would have been fantastic. After all, considering the number of times Jim and co appeared in the media all over the world as part of their covers, somebody
on the other side should have noticed the same white-haired guy constantly popping up under different names...
Also, no thread involving Leonard Nimoy and Mission: Impossible would be complete without this