The longevity point is interresting, and varies with sport, which I think means you probably cant really call on it in the discussion.
For instance a tennis player wont usually break through till 21/22 and is done by probably 32 in terms of competing in singles grand slams, they are on the road almost every week in competition. In sports such as athletics and boxing you are training for weeks/months to build up to one event and you have to turn it on at crunch time, these tend to have longer lasting careers, probably down to the amount of rest periods their body is given.
I think Murrays consistency along with the generation he is competing in puts him firmly in the conversation. Since the open era (1968) Britain had had 2 finalists in Grand slams over 40 years, Murray has been in 11 now in 8 years with surely more to come, winning 3 and Olympic gold.
I think Murrays acheivement of 3 slams is overshaddowed by the pure dominance we have seen for Fed Nadal and Djokovic. If he had got the results he has in Henmans era he would probably be held in higher regard.
