Personally, for every appeal for x-ray claiming they don't use x-ray, I always try to look into it and investigate further. There is always a chance that we're wrong. It's small, but it still exists.
And sadly, I have to agree with Miner. Pulling in stacks of diamonds in an hour isn't unreasonable (after of course if you factor Fortune enchants and Mcmmo). I can recall several occasions where I've done that. But it's also not likely, and warrants looking into. It's not like we just see the amount and ban them right then and there, it means their mines are going to be investigated.