Perhaps this was not fully "correct" of us, but we attributed "Maneuver in Armour" to anything NOT combat related as the wearer trains in the armour and is able to compensate, train harder, work within, etc. the limitations of the armour. The armour was designed for specifically for combat and combat related maneuvers and is geared towards those motions. However, it wasn't designed with Tightrope Walking in mind, or Leaping, Swimming, Dancing, Pole Vaulting, etc. We penalized accordingly.
And like Warl, we didn't want to tack on more penalties for wearing the armour. We had a few games where no one went above AT 12 (RM2) and players were just opting not to take heavier hitting PC's when we really could have used some. Paladin, Cavalier, would have been nice for a few sessions but we had to rely on NPC's for those times and NPC's are merely cannon fodder for our GM's