I'm not sure what the fuss is about

I've been sitting on this post for a while, hoping for some kind of update, but March appears to be when discussion of this shut down in relevant fora (that's the plural of forum for you Democrats out there -- I kid because I love). The Marines are getting a new amphibious assault vehicle to replace the AAV-7, a magnificent machine, but more than 40 years old:

So, back in March, the Marines went to hearings on Capitol Hill to discuss replacing the AAV-7 with members of Congress. Congressmen being experts on military affairs, that went about as well as you might expect. The Marines got pushback:

Lawmakers on Capitol Hill today voiced concerns about the U.S. Marine Corps' new amphibious vehicle, questioning the service's selection of wheels over the venerable tracked design.
Marine Corps leaders testified before the Senate Armed Services Committee's Subcomittee on Seapower to discuss modernization efforts in the proposed Fiscal 2016 budget request.
The Corps has identified its new Amphibious Combat Vehicle as its top modernization priority. The effort is set to replace most of Marine Amphibious Assault Vehicles that are well over 40 years old.
"Those vehicles are old, and they need to be replaced," Marine Lt. Gen. Kenneth J. Glueck, Jr., deputy commandant for Combat Development and Integration and commanding general of Marine Corps Combat Development Command.
"We will do what we can to bring some of those vehicles up to an acceptable standard, but to be the Marine Corps that you want for the future it is time to do some modernization."

I strongly suspect that the new amphibious combat vehicle will be built in different states than those represented by the senators who favor a tracked design. It is difficult to fathom how you argue against a 40+ year old tracked design over a new vehicle simply because the new one has wheels -- unless, of course, you're worried that the new vehicle won't be built in your state. I'm sure nothing like that would play a role in a senator's decision, though. The senators claim to be worried about a wheeled design, though:

Senators were more concerned, however, with the service's decision to choose wheeled technology over the more time-tested tracked design.
Marine leaders said the service has identified ground mobility as a high priority for the new AAV.
Wheeled-vehicle capability has advanced significantly over the past decade with technologies such as independent suspension, armor and variable inflatable tires, according to Thomas P. Dee, deputy assistant secretary of the Navy for Expeditionary Programs and Logistics Management.
Tests involving an eight-wheeled demonstrator vehicle at the Nevada Automotive Test Center have been very encouraging, Dee said.
"Performance was very good and for a medium-weight vehicle; it was equivalent to what we would get out of a tracked vehicle," Dee said. "It may not be as maneuverable or as mobile in off-road conditions in certain cases as an M1 tank, but is it certainly as maneuverable as we are going to get in that class of vehicle."
Sen. Mazie Hirono, D-Hawaii, said she was worried that first version of the wheeled ACV will be less capable since it is designed to carry 10 infantrymen instead of 14 like the current AAV.

The Army's Stryker vehicle has performed well and Congress has had no problems with its wheeled design. No one seems to think the Marines' light armored vehicle -- its primary recon unit vehicle -- is a problem:

The Soviets, and after the Russians, the British and any number of other nations have used wheeled troop carriers with great success. The capacity issue, with more vehicles carrying fewer troops each, is a good thing -- basic battlefield doctrine says "spread out." More people in one vehicle is simply an easier, richer target. And if the ACV is not as maneuverable in certain off-road conditions than an M-1 main battle tank? Surprise! It isn't a main battle tank, and neither is the AAV. The ACV is a vehicle to get Marines from ship to shore, alive, and then serve as their landborne transportation once they are there, and keep them alive in that environment, as well. Modern wheeled armored vehicles perform as well as tracked armored vehicles under most off-road circumstances, and better in urban environments. I don't think anyone would prefer the M-113 tracked armored personnel carrier over today's wheeled Stryker, for instance. The M-113, which it's aluminum armored, intended to keep it light, was not-affectionately known as the Bic, because it lit into flames at the flick of a thumb. (Aluminum burns really well, kids.)

Hawaii's senator, Mazie Hirono should know better. The 25th Infantry Division, based at Schoffield Barracks on Oahu, is the parent unit to a Stryker brigade or two, so she would be familiar with the capabilities of wheeled combat vehicles. I haven't heard her bitch about the Stryker. On the other hand, Hawaii manufactures pretty much nothing, so I know she isn't worried about losing manufacturing jobs. And the Marines a Kaneohe on Oahu would be using the AVC, replacing the AAV-7s they have now. Not sure what her problem is. Readers?