IronFlesh should be a natural armor value, not hp based. Maybe 2 pts of armor for head, body, legs for every pt of IF. In the end, a build with 8 IF could run around naked and still have basic light armor of 16 head/body/legs, or just wear light armor also adding its own value making it more of a medium wear.
This will allow even more viability for say a barbarian build as well.
It also would take away from IF being perceived as only useful when wearing heavy armor - as well as the fact people wearing heavy armor would have even higher armor counts now.