I agree. Something for the Brigades OTHER than 1 Brigade would be beneficial. Even if it where a wheeled vehicle with a 76mm/105mm sized gun would be better than the present situation. Puma would be a good choice for the Land 400 vehicle, so fitting a 105mm gun might provide a very useful capability...
Army looked at acquiring such a capability under the A21 trials, in lieu of operating a tank capability, but experimentation and "war gaming" showed that there are a lot of roles that ONLY MBT's can perform whereas "light tanks" or "armoured gun systems" cannot, hence the subsequent order for M1A1's.
However Army should operate such a vehicle in ADDITION to the tank capability. The current Government policy of purchasing high quality kit, but in-sufficient to equip ALL of Army has to end. I've no problem AT ALL, with high quality kit, but the kit (and associated supporting assets) should be purchased in sufficient quantities to allow Army to meet the direction given to it by Government, ie: simultaneous deployments of a Brigade AND a Battalion group in separate operational theatres, with EACH formation being capable of being sustained and rotated when necessary (ie: after at least 6 months but no more than 12 month deployment).
Army should be capable of meeting such a requirement across ANY spectrum of warfare, and this means Army requires 2 mechanised, motorised and Air Mobile brigades, when we barely have 1 of each at present (though we'll meet the criteria basically when the additional battalions come on line). A MUCH bigger equipment requirement than is currently being met...
I'm in general agreement with the idea of different horses for different courses, and especially a nation like Australia that is liable to have a lot of "away"-matches.
I think we should think of Light, medium and heavy forces, where light forces have high operational mobility and close to no tactical mobility - i.e. they get there fast to fight from prepared positions.
Now there isn't necessarily symmetri in the sense of a tank for heavy (armoured), medium (mechanised) and light (motorised) is as much as fighting from prepared positions without moving is kind of anathema to tanks.
Where I do see a need for light force is:
A vehikle that is:
1. Air portable and AIR SUPPLYABLE. (that limits weight - especially with the supply demand). But this will allow it to travel with light infantry and light artillery.
2. Armoured to protect against small-arms fire and RPG's.
3. Terrain mobility where tanks cannot go, because the only way this dumpster is going to survive MBT is by not meeting them.
4. Has the firepower to kill what they are liable to meet. MBT are best left to the dug in infantry. If weight limitations mean that that will limit it to a say 75mm and TOW-types, then so be it. The question is if the infantry wouldn't like such a beast when clearing out a jungle village "stronghold"?
If we are calling such a thing a tank, then no worries from me. Helicopters are the preferred solution at the moment; but they are of limited use in f.i. mountains AND they are supply heavy AND VERY expensive.
What I think we are in fact discussing is the need for a MEDIUM tank!
I.e. a vehikle for mechanised troops to cut of the heavy head of an enemy armoured thrust by trying to get behind their back, shoot up supply lines and destroy their artillery. That is in defence.
In offence it shall exploit the breaches made by the heavies - in particular the MBT - skirt the main defences, cut communications and head for command centers and such.
They must be suppliable - especially in fuel (as they are meant to drive rather than shoot).
Armoured to protect against MBT, that they might run into by mistake; but then in sufficient numbers (say a ration of 5-10:1).
Gunned to combat MBT as part of a combined arms force of infantry/artillery/cavalry - which might be acting as a bait to lure the enemy's MBT into a trap made of dismounted, mechanised infantry. I.e. they are not to seek out enemy MBT - they'll only get hurt by that tactic.
Good road capability, crossing ability over most bridges - especially where MBT can go - and simpler bridging equipment. This might mean a wheeled solution?