The best you can do is usually 7 to 10 health lost with about 30 shield. Shield is relatively a useless point. To catch up to a ranger, it generally takes at least 2 concs by the time you decide to use it.
1) If you're a good ranger, you will snipe the gunner out of the air.
2) 1 headshot kills the gunner regardless because his health is automatically that low.
3) Concing generally must happen out in the open, where the ranger always has the advantage in any battle. So arguments about, the gunner should only be in "his environment" is moot. Since concing only can occur in the open, where the ranger generally decimates gunners.
4) Splatter damage is now different for the gunner on his rockets then they were before - it takes at 5 splatters to kill a tech. In u2, it took 3. For rangers, it's 3 and it used to take 2.
5) Classes are faster than they were before (just slightly, but this speed increase nullifies the slightly faster rockets that the gunner has now)
6) What's even faster is suiciding and respawning in the direction you know the person is going.(of course you need a spawn point)
7) And yes, gunners is now a rarity for the most part. I've played games where 11 of 14 people are techs and the last 3 are rangers.
8) 1-7 are really moot because this has been discussed at length multiple times and FMI hasn't put concing in. I doubt it will be put in after we debate it this time either.
9) And no, I don't think the classes aren quite nicely balanced, but I will reserve to explain that after weapon reloads are fixed. See #4,7 for a hint at what isn't balanced.