Don't know how many ewes you have , i'm using 7yr old tex rams as part of a ram team 3 with 150+ and 8yr old nch again as part of a team 5 with 300 on the hill , so long as they are fit then I have no worries . I think you should as said ,buy a ram lamb next year as a safety ,ready to take over and then a second in 2017 , then you are not suddenly having to buy 2 rams at once