Yeah but the seats issue is less of a dynamic with the kind of combat teams being formed. Its no longer cavalry troop + infantry company = mechanised infantry but rather take a cavalry troop, an infantry platoon, a local forces section, a combat engineer section, a MP team, an intelligence team and give it to a manoeuvre sub-unit HQ (cavalry or infantry) and there you have a combat team.
The requirement to combat team hasn't changed. You still need the ability to lift the entire infantry battalion or there is really not much point. Adding in all other enablers in combined arms team increases the need for lift, not decreases it. Otherwise, what are all the other infantry in the company doing? Walking? The need for close combat hasn't changed, hence the need to be able to take an entire rifle company to the forward pits under armour if required. Having a troop lift a platoon+ on anything but an opportune basis (ie, driving back to the wash point after an exercise) is a complete waste of resources.
As for C2 the new vehicle will presumably support the BMS-D/CNR that the infantry are rolling with. For the human side of C2 since it is combat teaming rather than direct support the need for additional cavalry troop officers will be less.
In that combat team you listed above, you said it would be commanded by either an infantry or cavalry sub-unit headquaters? If its an infantry HQ, what vehicles are they driving around in? They won't fit in the ones already listed, and even if they did, they wouldn't be fitted out as command vehicles so wouldn't be very useful anyway. If its a cavalry sub-unit HQ, I wouldn't want to be the OC commanding a single troop. I wouldn't want to be the troop leader with an OC there to tell me how to manoeuvre my troop either. If that's the case, what are the other two troops doing? If they're combat teamed as well, you have the same issue with lack of lift, but simply magnified.
One of the key drivers for the basis of provisioning is manning levels. Troops of eight IFVs means roughly the same manning as current cavalry regiments and is the approved level by Plan Beersheba. If we have to build an infantry company lift capable APC troop (18 vehicles with 8 seats) then even with a two crew vehicle that will require 50% more manning in the troop. With a three crew vehicle it will require twice as many men in the troop.
This is not an issue, as that extra manning already exists, it is simply currently allocated to the infantry battalions. You take the 200 M-113s and 200 PMVs off 5, 6, 7 and 8/9 RARs, and you have a lot of extra manning to fill the lift squadrons. Otherwise, you are asking the ACR to take on the role of lifting at least three battalions without any extra increase in manning, when even current manning is only just sufficient to carry out all the non-lift tasks of the ACR. Plan Beersheba has 12 RAAC sub-units. There are currently only 9 RAAC sub-units in the Army. The sub-units aren't any smaller. Basic maths tells us that the manning needs to be reallocated to make this happen. Once the manoeuvre force modernisation review is completed, you will likely see a change in manning allocations.