We vasectomised a couple of ram lambs and never had a problem with them.
They tightened our lambing times up and we can keep them together no problem. I have had a couple of people ask me where they could get teasers this year so it might be worth moving them on this way and at Wilton sheep fair a couple of years ago a teaser made as much as a shearling ram! more than paid for himself. Big farms still use teasers but i'm not sure if a ryeland would get bullied; i wouldn't think so but dont know much about their temperament.
It may be worth a try, just be sure they are left the allotted time for the old sperm to break down