Mostly everyone thinks that Source 2 will make every Source game better. While that would sound great, it's not entirely true. Source 2 only works great on certain Valve games such as Dota 2 and I think CS:GO as well. But with TF2, I think porting TF2 to source 2 will only make things worse and not better. Or, I think you'll barely see any differences with it going from Source 1 to 2. It's at least what I've heard.