the balance factor should be close, its just how they achieved the weight reduction and the manufacturing method.
i have seen 2 airsal kitted (slap on kit job) big end bearings go out at well under 9k rpm so i'm leery of them.
oh yeah one other thing i forgot to mention- because of the stock airfilter on AV7's and them being piston port, they like to accumulate water in the bottom end. If they are left outside, or even sometimes if they are shedded... maybe something with condensation, i dunno. Either way i've worked on a lot of AV7's with rusty bottom ends, way more than other types of bikes.
I think in both of those failures mentioned above, there was corrosion in the needle bearing that caused them to fail early. Nothing you could feel, mind you. I was just thinking about it and forgot about that factor. So something to be wary of.