Jumping back into the technical/tactical arguments for a moment (while waiting for TCBF's round to land ;D), Infanteer has posted some Australian articles in the Infantry thread which basicly suggest we have things backwards. To paraphrase the articles: manoeuvre is the act of bringing us to battle, and the best way to prosecute a contact is by supression through fire.
The examples given include a series of 12 company attacks on a defended village over a three year period, using a fully instrumented range and MILES type gear, where the winning combination was to use 3/4 of the company to lay fire on the enemy, and when their will cracked, do the assault with an overstrength section! Similar results were found in East Timor in firefights between Australian forces and Indonesian and "Militia" forces during the initial deployment there.
If this is really the case, then a DF vehicle of any kind either needs magic bullets or a pretty large magazine to provide the level of supression needed. The MGS, with just 18 rounds on board, is a total non starter in this case, and I doubt the MMEV concept based around ADATS is much better. In fact, for the forseeable future, only a tank has the carrying capacity to supply supressive fire (and carry "magic bullets" in the form of through tube missiles) on the scale required. Even a light tank like the CV 90120 can carry 30 rounds of 120mm ammunition, plus the co-axe and turret mounted MGs, and if you add the LAHAT missile to the ammo mix, you have the ability to strike targets up to 13km distant.
The MGS seems to be more of a salesman's weapons system to get you to order more platforms from GD, rather than a means to adress any capacity gap in the CF. If the analysis in the Australian articles is correct, then even using the MGS as a dedicated Infantry support weapon on the model of the SBCT is a mistake, the support platoon will run out of ammo just when you need it the most! Given the sheer size of a LAV hull, it is hard to understand how it cannot hold a sufficient supply on on board ammunition. That alone should be the death knell of the MGS.