Every Avalon will be different just like every GPU will be different so they'll all have different overclock abilities. ASICs like these have hardware errors all the time by design and they're harmless. Fanspeeds at 100% are probably a bad idea because of the poorly designed fan layout in the avalon, it will make the thinner 25mm thick fan blowing to the PSU fail to work because of massive case air pressure and the air will be going backwards. Reported fanspeeds are very inaccurate on the sensors so don't bother trying to compare small differences in their RPMs. With my firmware, hardware errors are not counted as hashrate, so any rise in hashrate reported is a real rise in throughput and should be your ultimate decider in how high you go.
Anything else?