I don't believe that any common targeting can outperform PIF in melee, and that's why virtual guns won't improve your gun. Of course there are special cases, e.g. I think Portia has a feature that it treats disabled bots differently, and that might be a useful improvement compared to mere PIF.
Well, I see many bots treating disabled bots differently, and that’s not hard to be implemented with swarm targeting.
While PIF guns play a dominant role in melee, similar to 1v1, there are two types of PIF guns, one tuned to hit the majarity, the other tuned to hit adaptive movement.
Although there are not so many adpative bots in melee comparing to 1v1, they still contribute more score diff per bot than those you can easily hit. So if we were able to hit adaptive movement better, in melee, the score improvements should be noticeable.
Also melee adaptive movement is growing in popularity — virtual guns with swarm targeting will one day be an essential part of state-the-art bot.