It won't reduce the flavour whatsoever as there is still sufficient fat in the meat. The point is to get rid of the connective tissue more than anything else (which is almost flavourless). Another important point is that if you want your meat medium to rare, the fat inside will not render without considerable care using sous vide machines, so removing large chunks of fat inside the meat is important if you want a truly great roast. I've posted before about doing this precise thing using transglutaminase.
And regarding the effort required, it's hardly much. All it is, is trimming the meat (which one should do in any case for a roast depending on how it's been butchered), sprinkling on transglutaminase, rolling, and refrigerating. As it is I do steps 1 and 3 for a roast, and I leave my roasts to mature in the fridge for a few days in any case, so all I'd do here is add an extra day to the process in the fridge. 1 day sealed and rolled, and the additional days unsealed and maturing...
