Seems like the decisions are unanimous...OGun must go, Chambers must stay.
Let's do an honest evaluation of player circumstance as well:
OGun: Has a year of injury, an average year, and a great year. This shows good progression. However, he also plays opposite of the best DE in the NFL (IMO), Jason Taylor, who led the AFC in sacks on the year OGun played simply "average". Following JT's break out year, OGun is successful as teams are forced to focus on JT. How would OGun do without JT on the same line? I have to guess he would be good, but I doubt his ability to become a Kearse or JT. He is a good foundation for the future, but there are others on the team who can perform almost as good as OGun as long as JT is on the other side.
Chambers: Had a breakout season his rookie year, a slight sophomore slump (and a concussion), followed by an outstanding season last year. His production has been far more consistent then OGun, and he has done it with an inconsistent QB and NO additional WR threat, meaning he has had the talent to get things done on his own. Chambers is still young and continues to improve, making him a solid foundation for the future. With Boston in the backfield as well, Chambers may be the best WR this coming season. Boston is unreliable though, and cannot be considered a long-term solution on which to base a trade (he could decide not to care at any time). Until Boston proves himself to be a true workman, Chambers IS the receiving core of the Dolphins.
Defense is obviously better prepared to lose a very good player than the offense is to lose a great player. If OGun leaves, JT is still there and can be counted on. If Chambers goes, then Boston is our only real WR threat...and if he loses it, then our best WR is Derrius Thompson...this is a no brainer. I would take Ramsey and a 2nd for OGun, and if they want to throw in Gardner for Fiedler, even better. Let's get it done.