I have had Teague tubes fitted to a few old British S/S's but only when the gun was already/being sleeved anyway and I wanted to make the gun more user friendly.
I don't think I would ever have Teagues fitted to a good original set of barrels unless the customer requested it.
I certainly wouldn't do it if I thought it was going to reduce the gun's value regardless of how use-able it made it!
I have been toying with the idea of having my father's Blanch BA SLE rebarrelled in 16g (the original barrels are toast) and would certainly have those Teague choked before proof. If you have the chance to shoot early season driven partridges and late January wily pheasants, you need very different chokes and I always shoot better with the same gun for the whole season, September to February.
