Having to have a variety of classes is an advantage but 25mans can get all bufs without even thinking about it most of the time. For a 10man to get all or even most bufs there has to be a whole operation of research and since the roster is limited, often not more than 11 or 12, there is a process of several months for a guild to reach all or almost all bufs. And often due to people leaving, a new expansion or patch that makes a spec have to change or other similar reason, it may be broken.
So a solution would be simply to grant more bufs to 10mans. For example if a class can give 2 bufs but 1 of them is locked to another spec, to be able to give both bufs. It will not destroy the variety of classes, but it will make it easier to reach 25man parity. If 2.5x the bufs may be extreme (potentially), then 1.5% the bufs only might be a start.
I know there is a technical issue of justification. i.e. which would be the 'lore' or other justification reason that would explain it? If 25mans would get their bufs anyway due to sheer numbers maybe even them should get the increase.
So a solution would be simply to grant more bufs to 10mans. For example if a class can give 2 bufs but 1 of them is locked to another spec, to be able to give both bufs. It will not destroy the variety of classes, but it will make it easier to reach 25man parity. If 2.5x the bufs may be extreme (potentially), then 1.5% the bufs only might be a start.
I know there is a technical issue of justification. i.e. which would be the 'lore' or other justification reason that would explain it? If 25mans would get their bufs anyway due to sheer numbers maybe even them should get the increase.