we all know why we don't run these in 6s so there isn't any reason to talk about that, but i feel like the way its used in pubs is also important for discussion because it demonstrates to us what kind of shit valve is fine with happening in the game.
these mini sentries divert the attention of the entire other team, especially on the koth maps, regardless of what class you're playing, even if it deals with the sentries decently. if a soldier is shooting this thing even from range, which the soldier has no choice not to do because it's impossible to miss, that makes that soldier vulnerable to the real human beings that are playing the game. it prevents you from doing shit, particularly things that take some degree of skill such as rocket/sticky jumping, just because 1 guy is running this and it never leaves. it really makes no sense how valve could allow something so easily played to have such a monumental effect on the things that are more difficult to do in tf2.
uncle dane would probably think as a pub engineer main, amongst people who play medic and heavy in pubs, that if someone is playing a class that counters yours, that you need to switch to a class to deal with it. now that sounds like some overwatch shit and goes against why tf2 outshines overwatch, which is that you can if you're skilled enough deal with anything in the game as your class so long as you have a better skill set than the guy shooting at you. for instance if you're playing spy, you can amby headshot the pyro, if you're sniper and someone's in close range it's still possible to headshot or if you're playing soldier and you jump an awful scout, you can still kill them.
when it comes up to engineer though, against scout for instance, this doesn't exist because it'll always win 100% of the time. the engineer's skill level doesn't even come into play because the engineer isn't even the one playing the game. it's the game playing the game.
i think they should nerf the gun severely in terms of either firing speed or damage and then buff how much health the engi has (175 should be fine, but maybe 200 even would be good) and also the speed so it's comparable to the medic. i think this retains valve's vision to make the engineer more mobile and increases how enjoyable playing engi would be, considering this encourages you to actually play the game to be effective.