I guess the size of the machine is quite a factor. A DRO on the topslide might be easy enough on a big lathe but a nightmare of fiddliness on a small one.
Would be good to have a lathe with a DRO though. I once saw an immaculate Myford Super 7 at a model engineering exhibition in England with one on it- probably just the two main axes if I recall. The lathe had a pristine paint job in an unusual pale beige colour and it all added up to an unattainable little object of desire that has had me wanting to DRO-ify a lathe ever since.
The nearest I have got to it is that I have a Myford ML10 which had X and Y axis scales on it when I bought it. It should be just a matter of getting a display and hooking it up. The ML10 is in excellent condition. Or I should say 'was', as it was right under the part of the roof of my workshop in France that blew off. I haven't yet been over, and it remains to be seen what kind of state the ML10 is in now or if the DRO scales will even work.
Anyway, I guess that's just a very round-about way of saying Yes! to DRO's on lathes, and I'll be following this thread with interest...