Ah, the old arguement eh?
I've got both, a mid 60's horse mc28 and nc35 (as well as a Transalp) so here goes;
Running cost wise there is no contest, the '28 is probably around 4 times more expensive to run and that's before you factor in the all to frequent rebuilds...
Speed wise there is nothing in it, to be fair any of the late 80's/90's grey import sports bikes are all much of a muchness, there isn't enough to make a difference, on the road it's the crazy man who wins, on the track the guy with the most skill. The stroker is also harder work and a lot less forgiving, whether that's good or not is personal preference.
But for me (on the track a least) it's got to go ring-a-ding, on the road it depends, when it all comes togeather the '28 is the best bike in the world, the other 90% of the time it' a pain, the '35 is always very very very good whether it's a rainy trip to work in the dark or round Donington track.
If I'd got to choose one bike, it's a 4 stroke, 15000 miles a year to work and back decides that for me, if I can have one just for fun it's a stroker.
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread