Mark,
One of the issues with LED's are that they generally direct light in one direction. Superbright LED's does sell the 90 degree ones, but I don't know how they work. Since you can get to the little bulbs from the front speaker grille, without pulling the dash apart, I was less worried about longevity. And the little clear bulbs throw enough light for the heater control levers anyway, so there is not an inherent dimness issue.
My two cents is to leave them be, just in case you asked.
Mike Mizesko
Columbus, OH