So I gave that defensive HK21 class a shot. Its my first time building a class with an HK21; up until now, my experience has solely been with guns I've picked up. Sadly, I only managed to get two full games in before my wife said "Hey, the dogs need to go for a walk!"
Game 1: Domination on Hanoi. Started off great, but tanked towards the end. We somehow managed to win; at the end, I looked at the scoreboard and realized that I was the only one who ended up positive. I guess I have Mr "6-and-24-with-5-captures" to thank for the win, but it was still a frustrating experience to get overrun. At least we won, despite me playing rather poorly and my teammates apparently not knowing how to fire their weapons.
Game 2: Domination on Launch. I'm still getting used to this. I screw up the opening move; I don't realize that there are
two enemies on Bravo (one was prone behind the other) and get killed because I stop firing after killing the first. They cap the point. I try to rush back to Bravo, but they've set up camp and I get killed twice trying to get back there before I decide it's not worth it. At this point my teammates have managed to lose Alpha as well. I switch to a Ghost class, and get killed by a guy camping prone in the hallway out. I'm not doing well, and rage quit at 1-10 after a couple minutes. Not proud of that, but I can't take it back.
Game 3: Join-in-progress. We're being dominated. I quit before picking a class.
Game 4: Another Domination on Hanoi. Ahha; now here it clicks. I move slowly; I pick my battles. I trust the hipfire accuracy of the HK21 (much better than I expected!). I try to stay near flags since I can't move very fast; I slowly move around and try to hold down the buildings. It's a very chill, almost zen-like method of playing the game. I end 36-4, with 1 cap and 8 defends. We win handily.
I feel like it's a good class, but it only works on defense. I think I'll keep it around for those times when I just want to chill and not really take the game seriously. It's definitely a total "try-hard" class; not nearly as exciting as a rushing AR or SMG, but it does get the job done, and I could see it being incredibly effective in a more linear game mode like Demolition.