I still have reservations about the mines being "completely invisible" to anyone but the Op. I like having the Op being a spotter, but not allowing even the tiniest of giveaways for careful players is going to promote even more use of Ops.
Would have liked all command posts to be capturable as well. They have a great deal of use and it would have made for some more interesting strategy.
Between mines, health regeneration, and being able to grab ammo at a command post, it's starting to look like Ops and Engineers may end up being the meat of this conflict.
Pretty much the only reason the base command posts are not capturable is that its the protected spawn point, and only place that you can change classes. If we could capture it, then the team could be stuck without the ability to complete objectives. Also given that the main spawn point is a safe haven, that would have to be removed to allow the command post to be captured, allowing spawn camping to occur. In terms of the mines, if they were visible to all, they would be useless. How many people would walk into a mine if its right in plain view. This forces teams to have operatives with them, but they can't simply have all operatives and engineers... they will still need soldiers and medics. Soldiers are the only class that can breach... and without medics, you won't survive long enough to coomplete your objectives. All in all, no need to be worried, looks like SD put a lot of thought into game blanace.