The Abrams seem too fragile to me, based on first-hand accounts in the current action against Iraqi forces. 'Thunder Run - The Armored Strike To Capture Baghdad', by David Zucchino, for example provides account after account where the Abrams takes RPG after RPG at fairly close range without major damage (unless the hit is directly in the rear vents - a known vulnerability). Those 70-ton beasts can dish out and take a major pounding and keep on ticking.
That said, the actual accounts of recent action in the Iraq war demonstrate that US forces opt for overwhelming force in the face of adversity whenever possible.