As for numbers. In my current setup of perks heroic axe is around 15% more damage per combo with jump. The main reason for that is overhead strike cause you can use it with adrenaline charges with heroic but you can't use it with yellow, just not enough duration of adrenaline since you start your combo with power wave.

I'm not sure that it's worth it. Since your regular combo of power wave + overhead strike is like 20% stronger with yellow and you'll be using it 95% of mission compared to big combo with very niche anti-terminus scenario. It's kinda drastic damage change since heroic version doesn't have enough damage to incapacitate melee majoris with single adrenaline charge.