The Immediate problem with Breakthrough. Because defending can net you a round win, currently there's no incentive to capping the breaker. Sit back, let your opponent take it. Defending your vault position is a much easier task and takes less coordination. there are so many zoning grenades at your disposal to cut off choke points. Other problem is because it's 4v4 you can easily wipe the attacking team with a super. My immediate suggestion would be capping the breaker nets 1 pt, a successful vault defence nets 0 pt, but a successful vault attack nets an additional 1 pt. This would incentivize taking the breaker and attacking. Other suggestion would be to increase to 6v6 teams. Where the loss of a teammate is only 16.7% of your team, instead of 25%. In terms of potential, I think it's an interesting mode. Rift has far more strategic depth though.