I talked to Harman about the so-called cap problem a while back. There were apparently some weak parts, not an endemic problem, and it wasn't even in the 334-336 series. The whole re-capping thing is audiophile paranoia nonsense. Just think about it... capacitors are commodities, they're not made special just for Harman. If Levinson amps need new capacitors so often, why don't all other class A/AB amps?
Not all circuits are created equal, even if many of the components used in competing designs are identical.
As a previous owner of a 336 (which I absolutely adored) and experienced the capacitor problem, I can sympathize with those who are leery of the 3xx series of amplifiers.
It's a nerve-wracking experience trusting your mega-buck, 100+ lb baby with any of our shipping agents. Mine luckily was repaired and returned without incident, and sounded better than ever upon it's return. Sadly, I will not be considering another 3xx.
With that said, I wouldn't hesitate to buy a 4xx or 5xx ML amplifier.