Personally I can't get away from medium because of how effective roll dodge is.
What can't be dodged (for the most part) will have a 25% reduction from shuffle.
That's really all I need
You are right and i like medium gameplay too.
But on heavy you don't need roll dodge that often, so you can stay close to your target and keep attacking.
How long does a dodge roll take? Maybe 2 or 3 seconds until you can attack again.
On heavy you can use these seconds to stay offensive.
In the end i also think you don't lose damage on heavy.
Think you will see a lot more penetration this next patch now that it's no longer wasted on shield users. May not want to just eat the hits in heavy any more. Roll dodge, block, and flat damage reduction (evasion, protection, crit resist) will be what matters most.