I guess this might be the solution:
In Russia, developed a unified platform for armoured combat
MOSCOW, October 26. (ARMS-TASS). In Russia, for the rearmament of the army is developing a unified platform for military wheeled armored vehicles, medium and heavy tanks, the new generation, said korr.ARMS-TASS General Director of "Military-Industrial Company" / MIC / Dmitry Galkin at "Interpolitech 2011."
Work on the new platform performs a part of the MIC Arzamas Engineering Plant. "Right now, the company's activities focus on development and design work to establish a combat wheeled platforms, ordered the Ministry of Defence - said Galkin. - This is a fighting machine the next generation."
According to him, the new machine "is not similar to any modern APC." "This is not an APC. We call it" combat wheeled vehicle, "because at its base will be created as APCs and IFVs, and a tank or a heavy gun," - said the head of the MIC.
He explained that under the "modernization and upgrading the Russian Armed Forces, the Defense Ministry has ordered while three types of development projects: on wheeled vehicles - the company MIC, the average caterpillar -" Kurgan "and the heavy caterpillar -" Uralvagonzavod. "At the same time the Ministry of tasked to ensure maximum unification of all three cars.
"All of these machines can be unambiguously standardized by CICS (onboard information control system), aiming systems, communication systems, combat modules", - informed the head of the MIC. Two prototypes were wheeled vehicles to be built by 2013, he said.
Galkin said that under the "permitted capacity", plan to use advanced foreign experience in this field. "We are now open in this respect, and where we allow the defense and national security, we use those developments that exist in the world" - he said.
The head of the company said that implemented development projects included in the state armaments program through 2020, created a new generation of armored vehicles will be supplied to the army under the program.
"In Russia, for the rearmament of the army is developing a unified platform for military wheeled armored vehicles, medium and heavy tanks, the new generation, said korr.ARMS-TASS General Director of "Military-Industrial Company" / MIC / Dmitry Galkin at "Interpolitech 2011."
So that means to me that there will be a military wheeled armoured vehicle for light and medium, and 'tanks' for medium and heavy... in this case tanks simply referring to tracked vehicles.
"According to him, the new machine "is not similar to any modern APC." "This is not an APC. We call it" combat wheeled vehicle, "because at its base will be created as APCs and IFVs, and a tank or a heavy gun," - said the head of the MIC."
So the Kangaroo/Boomerang will not just be a 25 ton amphibious APC, it will be an APC AND IFV AND a tank of gun armed fire support vehicle... this suggests a troop carrier version (BTR) and a more heavily armed IFV version (BMP/BTR-90) like vehicle.
This sounds a little strange as the Kurganets-25 is a 25 ton amphibious vehicle for the same units, but I think they will likely have tracked and wheeled versions of all vehicle types where possible in the medium brigades as in the middle of Siberia the ground conditions will mean the whole medium brigade will be tracked (kurganets-25 based), while in western Russia the better roads means wheeled vehicles can dominate as they are cheaper to buy and operate and are much faster when operating on roads.
"He explained that under the "modernization and upgrading the Russian Armed Forces, the Defense Ministry has ordered while three types of development projects: on wheeled vehicles - the company MIC, the average caterpillar -" Kurgan "and the heavy caterpillar -" Uralvagonzavod. "At the same time the Ministry of tasked to ensure maximum unification of all three cars."
So MIC will make the medium wheeled vehicles (Boomerang/Kangaroo, and also the light the Typhoon), the medium Kurganets-25 and Heavy Armata will be developed and made at UVZ.
On another thread there was posted a board showing engines for light wheeled vehicles and it included the fact that 350-450hp engines would be used with the Typhoon light wheeled vehicles and that the lighter engines would be used on 4 wheeled Typhoons and the larger 450hp engines on a 6 wheeled Typhoon...
Perhaps that is your answer... the Typhoons will likely be amphibious and the 4 wheel model will be the BRDM equivalent, while the 6 wheel will be the troop transport (APC/IFV), direct fire support (Tank), ATGM carrier, air defence vehicle (with 8 ready to fire MANPADS and HMGs as used in the Phoenix turret on the Vodnik?), etc etc.