I bought a USED Micro 335, 3-4 years back. Never had a limb break but had 3 sets where 1 limb got weak, throwing the bow out of tiller. Excalibur replaced them all UNDER LIFETIME WARRANTY even though I wasn't the first owner. They finally redesigned the riser and sent me essentially a new bow. I have never had an issue since. About a year later I bought a new Micro 355. Not 1 second of trouble, but that doesn't mean I never will have, so I bought 2 sets of limbs, which I have never needed for either bow.
If you are looking for a bow that will never have a problem, you are fooling yourself, so IMO what you want is a COMPANY that will stand behind its bows with no hassle, no blaming the shooter, and no excuses. For me, Excalibur has been that company.
Of course the best warranty is the one you never need, but since every mechanical device is subject to failure sooner or later, HOW the problem is handled is as important as the warranty itself. There are several companies that have great warranties and CS, so I would check them out.
Now I hear about some limb problems with the Micros again. I tend to think they are overblown but even if they're not, i have complete confidence in my bows and the company behind them.