I've never seen that rule actually employed in a game, and would always vote against it.<br/><br/>As for your critical rule, let me see if I understand:<br/><br/>Using a greataxe with STR18 as a simple modifier. A hit does 1d12+6 damage. On a normal crit, it would deal 3d12+18 damage, but under your rules, it does (1d12+6)*3 damage instead?