We can calculate the difference.
Do you remember what was the number on Tectonic when it was maxed? what % chance per how much ewd?
Quick math for your setup, Colonel has always the same amount of damage, + snownstorm combo it results in avg damage of 276. And it is 1 frame faster than 2h axe (so 16% multiplier to spammable damge (irrelevant for manual cast SOR), and chance to proc). Also 10% deadly strike.
Colonel base type ed bonus is (0.11 per Strength)%
Two endgame 2h choices:
both 2h axes (0.16 per Strength)%
non eth Gotterdammerung
average damage with 6 jahs = 662
Area Effect Attack (100% chance to cast 50%wdm aoe 5 yards)
Mega Impact 25% chance to cast -7% enemy phys res debuff
Grief
runeword (berlemgulbur) in sacred labrys superior 60% ed base non-eth
average damage = 611
slows target 20%, max all res 1%, 5% dodge
for SOR if we count 20% more damage (to reduced cooldown), then total damage goes up by 20% (for weapon alone that would be 730)
thunderfury proc is lightning which will be nulified by passive
So basically, question is, how much more proc chance from tectonic will you get in comparison to 2h setup and does it outweigh the difference in base damage, which is over doubled, among other stats on weapons, such as AOE proc every swing, mega impact, or that reduced sor cd.