Just some food for thought. Note that all Damage Numbers were taken in the T3 Guild Training Hall against effective targets with a damage bonus of VH, to make any difference most evident.
Omega Tortofist (Lv. 9)
-Punch: 153
-Projectile: 202
-Charge Impact: 264
-Charge Ticks: 198
Nether Cannon (Lv. 10)
-Punch: 153
-Projectile: 206
-Charge Impact: 268
-Charge Ticks: 198
Screenshots:
http://steamcommunity.com/sharedfiles/filedetails/?id=289970399
http://steamcommunity.com/sharedfiles/filedetails/?id=289970618
http://steamcommunity.com/sharedfiles/filedetails/?id=289970524
http://steamcommunity.com/sharedfiles/filedetails/?id=289971736
http://steamcommunity.com/sharedfiles/filedetails/?id=289972167
http://steamcommunity.com/sharedfiles/filedetails/?id=289971042
http://steamcommunity.com/sharedfiles/filedetails/?id=289972531
You will find that the largest differences will be the furthest away from haven you get. D23 is the intermediate between S5 and S6 - where the damages just start to differ. Try taking more damage values in S6.
If you look at the wiki values - everything below S5 is almost identical for both level 10s (only off by 10 damage points max). However, S6 has a difference of of 32 max (in which the damage is about the same by the heated level 6-8 range).
Also - there are 2 other threads discussing these numbers. Why not comment in one of them?