I've never bought a first hand "alpha", but I've enjoyed many. In some occasions I did buy units that had some flaws (some time knowing it beforehand, some other times I didn't), so I've used the repair service under warranty many times. Swarovski, Zeiss and Meopta have been stellar, always repairing for free and, not only that, but also sending back the repaired unit for free and in some cases doing more than was initially intended at no extra cost and also including spare parts for free (say a brand new strap, rain guard, objective covers, etc.). This gives me peace of mind when buying a 2nd hand top of the range. I know that, even if the unit I buy is not perfect, it will be repaired and bring back to full usability.
I've also had good experience with Vortex. I once bought a Viper HD that looked good, but after using it for a while I found it to be slightly misallinged (I started having headaches after using it), so I sent it in and got a brand new unit. So, there you go, another reason to buy a 2nd hand Vortex with confidence.
On other occasions I've bought binoculars with missing bits, especially objective covers: sent an email to Zeiss and Steiner and in a few days got brand new covers for free, and I have to say the objective covers on the Nighthunter are a thing to behold, they're made of at least 2 or 3 different kinds of rubber and plastic plus a fabric strap, I wouldn't be surprised if they chared +30 € for them. So great service from Steiner there too.