Yea, the whole team swapping to destroy enemy fortifications thing is pretty lame. People should be ashamed of themselves.
I saw a guy build this really tall tower with a spiral staircase going up for the intel and several people were on top of it defending their base. It was a pretty cool tower, too - must have taken the guy half an hour to make. I was on the other team, but I managed to get over there and run probably halfway up it before they noticed I was there and I got shot lol.
Then someone swapped and ran over and dug out the foundation and made it all collapse.
The game needs some kind of option to disallow new team joins from destroying blocks not made by them for X time after joining, so you couldn't swap over destroy their fort and swap right back. People could still grief by staying on the team a while then doing it, but at least it would stop the issue of people swapping back and forth just to destroy the enemy fortifications.
I've also seen evidence of cheating, but im not sure if its cheating or some kind of bug. A guy was running across the map repeatedly falling, and shooting him repeatedly never seemed to get anything to hit (even if I seemed to hit him, which was difficult since he was constantly teleporting into the sky and dropping), yet he was able to shoot everyone else fine.
Another time I was deep underground digging a tunnel under a mountain that the other team had a fort on (plan was to tunnel up right past them and shoot them from behind) and started getting shot, I ran around and noticed bullets coming through the roof, even though there was like 10 solid tiles between me and the surface. I went back inside and this time I sealed up the tunnel behind me before I went deeper just to make sure someone hadnt come behind, but when I got in there I got shot by the same person (an anonymous Deuce).