I know I like Chzech Nymphing, but to me it is not fly fishing as I have almost no fly line outside the rod tip. I also love normal Nymphing and I think this IS fly fishing as the fly is delivered by the fly line.
In England for nearly 5 hundred years fly fishing was done with fly paterns that were in fact wet flys, tied spider style or palmer style, on the end of horse hair lines, then someone worked out how to get a fly to float and for about 60 years some snobs decided that if it did not float it was not fly fishing. I know it is not well recieved by those that only fish the dry fly but it is a fact that the dry fly is the Johny come lately in fly fishing.
So I guess in my view if the fly is delivered by a fly line it is fly fishing, if the bobber or bubble float provides the momentum to deliver the fly it is fishing with a fly rather than fly fishing. Mind you I have to say it is a pleasure to watch someone who is skilled with the spining rod.
All the best.
Mike