Did some calculations yesterday to see how much damage you would have to deal as a gunboats soldier against a targe, boots and eyelander with maxed heads that is being healed by a medic. The demo's HP is going to be (150+25+15*4) 235*1.5 which is the overheal, a total of: 352.5 minus valves roundoff to 350.
Now lets add the explosive resistance to the HP: (maxHP/resistance) 350/0.6 = 583.33~
With the 3 hour nerf: 500HP
We also have to count the baseheal/sec which is 24, so depending on how many seconds it takes the more HP the demo gets. The fastest way to kill the demo turns out to be to shoot 4 rockets, then hold and shoot one, reload one, and so on..
This takes about 14~ sec. So the heal amount should be 14*24 = 336hp. But here's what's interesting, because that the heal rate is relative to the shield one has to apply the resistance to the heal rate. 24/0.6 = 40hp/sec
So instead we get 14*40 = 560hp
(actual healrate relatively + actual MAXHP = damage that has to be dealt) = 560+583 = 1143hp
This means it takes 11 perfectly placed rockets close range (112dmg) on a demo that's running almost as fast as a scout. On the contrary it takes 6 rockets to kill a constantly overhealed heavy that is practically standing still.
If you do a quick calculation with the quickfix +40% healrate buff you get: (24*1.4) / 0.6 = 56hp/sec. A rocket can be fired every 1.12~s, 1.12*56=62.72. So every time a rocket can be fired the medic has healed 63~hp, which means if you deal less than 63 (not the in-game rocket hitnumber) you are unable to kill the demo. Assuming the demo can survive the first 4 rockets.
Even tho a gunboats soldier would actually kill himself before killing the demo if he stands close enough to deal the max dmg 112/rocket, it ends up taking 21s~ and 15 rockets to kill the demo off. In a real situation you obviously wouldn't deal this much dmg and most likely run out of rockets.
quickfix example: https://www.youtube.com/watch?v=TFOFWH6m3GQ
That 0.7 nerf seemed more reasonable..