First of all, it's rather important to remember that properly fit armor was not restrictive to movement actions. You could do somersaults just fine in plate armor if you had proper training (of course, added weight or improperly fit armor could factor into this).
Secondly, Light armors and Medium Armors made of Mithral are superior to Heavy or straight Medium Armors. No movement penalty, no dexterity bonus limit, negligible armor class difference and, most important of all, you do not get skill penalties (no drowning, no problems with escape artist and so on).
Suggestion:
Improve armor class bonus for Medium and Heavy armors to make them worth using again.
Lessen dexterity limit.
Replace movement penalty with Fortitude save when engaging into strenuous activities for extended periods of time.
For example:
SRD 3.5 wrote:
A character can walk for more than 8 hours in a day by making a forced march. For each hour of marching beyond 8 hours, a Constitution check (DC 10, +2 per extra hour) is required. If the check fails, the character takes 1d6 points of nonlethal damage. A character who takes any nonlethal damage from a forced march becomes fatigued. Eliminating the nonlethal damage also eliminates the fatigue. It’s possible for a character to march into unconsciousness by pushing himself too hard.
Running, fighting, swimming beyond (CON bonus + 1) minutes in Heavy armor requires that Fortitude save is made (DC 10, +2 per extra minute beyond limit). Failure means that the character becomes Fatigued.
Continued activity while Fatigued: Exhausted.
Regards,
Ruemere
