Doubtfull in our time wether any armor is really survivable considering the *Specially designed Tank rounds,ATGM'S and mines which exist..then too...overhead CAS.
Janes intel revealed that the Russkies did give the Serbs *Depleted Uranium tank rounds in the Balkans to use.
Its a debate as to possibilty on some newer generation French or Russian ATGM's being slipped into Republican guard to see how they performed.
Israel went on a turret modernization of its Merkava series...also mod their U.S. M 60's with new turrets.
Merkava 4 is said to have a turret specially designed to defeat *above attack ATGM shots.
I would imagine Stryker is an attempt to succedd the current LAV design..which is very mobile and efficient.
Track vehicles numerically go out on some math curve as maintenence in the field goes.
Canadas Patricia's went to several wheeled armor designs..they were succesfull in Afghanistan..the hint is...wheels get their and back better than track.
I believe in playing the percentages. With RPG's as easy to get as Cokes in many places, I'll take the vehicle that defeats them. Note that the hit from the Kornet ATGM in the Iraq campaign did not cause a catastrophic crew kill - and a retrofit supposedly has solved that weak point. If you have a vehicle that only your most sophisticated weapons can kill, why wouldn't you use that so's you can focus on the most lethal weapons on the battlefield?
We've tried lighter and more nimble against heavy in WWII and it didn't work. Only the fact that Detroit could overwhelm Stuttgart in production saved our nuts.
If the FCV could be built as specified, it would be a great leap in our capability. But so far no one has invented the technology to make a 20 ton vehicle survivable.
I agree that the days of Abrams invulnerability are numbered, given the newest ATGM's coming on line and the future over the horizon precision weapons. On the other hand, there is some pretty interesting research into new armor approaches. I suspect the age old seesaw between offensive firepower and defensive armor will keep bouncing back and forth in the future.
Don't get me started on the Stryker. The supposedly overweight Abrams is much more nimble - shorter turning radius, more stable on an incline and faster. It's an open question whether Stryker can defeat an RPG, or even a heavy machine gun. The whole reason for building the thing is to gain C-130 deployability. So, it's being deployed to Iraq by - you guessed it - ship.