This is a bit "back to the future", but I found a picture of a proposed "Rapid Deployment Force" (RDF) tank form the 1980s. The idea at that time was to be able to insert a force into the Perian Gulf to prevent an invading force from the USSR from establishing itself in the region. The force needed to be almost as quick to insert as an airborn assault but have enough protection, mobility and firpower to take on an enemy mechanized force such as an MRR. This dosn't sound too different from the SBCT or the FCS program, but the "bottle" for that vintage of wine was tracked light armour.
If memory serves (and please help out), this prototype was by AAI, and featured the ARES 75mm high velocity cannon. The cannon fired telescoped rounds (i.e the projectile is embedded in the charge, not stuck in front the way we are used to) in single shots or three round bursts. the two man crew was down in the front hull, and most of the mechanical components were derived from the M-113.
With today's technology, the FCS would be vastly superior to anything available in the 1980s, while mobility and protection would be much improived as well. I am not too sure about the gun, but it certainly seems like it could deal with anything less than an MBT, and the low profile would make it hard to see. An idea still worth persuing or one who's time has come and gone?
Truly one of my favorite AFVs capable of taking out a T- 72 frontally or being used to shred hinds with ! It had in that role a 90 % hit rate with a 3 round burst . It could be used a light artillery spg or as already noted as a AAA piece.
14 tonnes with out applique armour as for speed I promise you all the speeding tickets your lil heart desires! ;D