Thanks to Debo's 4v4 testing party last night for the feedback. Heart of the Mountain worked better than expected for 4v4, although it needed some tweaking:

1. Two clamber routes added that lead to Top Nest to further decrease its strength.
2. Increased radii of stronghold zones in Red and Blue yards.
3. Rocks added to both yards for slightly more cover.
4. One of the two BRs replaced with a Carbine for variety.
5. Minor camera tweakage.
6. Chromed-out pig hidden.