Differences in Hollowtech II bottom brackets?
 

I should probably replace the bottom bracket in my mountain bike. It's got a XTR FC-M970 crankset, and I believe matching bottom-bracket.

Does anyone know what the differences are in HT2 bottom-brackets over the years/models?
Deore is ~$17, XT is ~$25, Saint is ~$30.

Are there differences in sealing or bearing quality? I know somewhere Shimano changed the outer size so I might need a slightly different tool.

Last two Shimano BB's I bought came with a plastic adapter so you could use a standard HT2 Tool to tighten them, so despite the smaller size of the thread, a new tool shouldn't be necessary.

As for quality differences, IMHO given how cheap Shimano BBs are, just get the one you're comfortable paying for. For me on road bikes that's the Ultegra version. The differences seem to be mainly weight. For MTB, maybe the seals are better on some, but honestly in my experience there's really not much difference between them.