They were originally named after the TF2 classes and are obviously influenced by them.
In addition, saying GG2 is "completely unrelated to TF2" is completely false:
Changing the classnames from TF2's to GG2's doesn't suddenly make it not related to TF2 at all. I understand that you've tweaked things (some forced, some intentional), but that doesn't change the fact that the server is basically Blockland's equivalent of the VS Saxton Hale Mode in TF2. Just because you're trying to stray away from TF2 and avoid the "LOL TF2" to-do list doesn't mean you shouldn't implement some of the great gameplay features it has.
To go back to my original point, yes, I'm suggesting that the medic should be a little faster and heal in small amounts over time (he is a medic, after all).