The hub obscured thing is not really a rule, but more of a quick and dirty guideline. I wouldn't base my decision on that alone. Think of it this way, any number of stem lengths can put your bar along a line from your hub to your eye, but most of these will not be ideal positions. I'd say if you feel too stretched out, then you probably are. Try a 100mm. Personally, I like to run 100 mm for off road, and 110 or even 120 for road riding, although all can work for me. With the longer stems I spend less time on the hoods, and more on the ramp of the bar.
And as a side note, I love my Thompson stem. It is like a peice of granite-solid.