Quoted from PinMonk:

Light boards, light boards, light boards. If they're the unbuffered 5v or 7v ones you're looking at $500-700+ to replace them all out of warranty, and you WILL eventually have to replace them all.

Quoted from libtech:

I hear avoid the green LE, go for a ruby red or standard, the LEs had lots of playfield wear (the whole sticker cover up stuff) and lightboards too of course on them as well.

Quoted from RobKnapp:

Frank at JJP told me if you don not get the 75th WOZ RR 2.0 with a new power supply and monitor and totally redesigned chip for the light boards I was making a mistake that the 2.0 is the way to go. Good luck I hope that helps .

Quoted from knobstone:

I bought the WOZ RR edition in West Virginia, picking it up in a couple of weeks. I believe it has the 7.5 boards. Build date is 10/01/14

Quoted from PinMonk:

Once they go, they all start going. I was rock solid for a couple years, then almost a year of replacing boards as one after another failed. Even after replacing everything, 5 of the replacement 7v buffered are out now. They do fail, and once it starts, it's a hassle.

Quoted from iceman44:

I’m not sure what the exact cutoff was but I’ve got the 7.5 boards and production date was late Oct of 2013
They changed boards during that month

Quoted from RobKnapp:

(Pimp77) you always down vote any post I make regarding being mindful of purchasing a older WOZ . But you never are specific or explain why you down vote. I have done my research on everything WOZ . I am just posting what I have learned and why I personally want an updated 2.0 WOZ . Older WOZ machine can not even run the new 6.5 code. It causes lockup my friend owns a 2013 and he has to run an older version of code . Will we ever get to install a lockup-free version of WoZ 6.xx on the original run machines that have problems with the newer Linux kernel introduced in all 6.xx versions (5.xx and below were fine)? .

Quoted from andrewket:

I picked up a RR WOZ today, manufactured 12/2015. Its working fine, but I wish I had found this thread before the purchase. I was already talking to a distributor about a NIB purchase (Black Friday) when one popped up for sale near by so I jumped on it to save $1300 plus a few mods. I sure hope I didn’t buy myself a bunch of problems. If I end up having to buy an upgrade kit for $700, I surely would have bought new.

Quoted from PinMonk:

Ruby Red has newer a newer PC board and probably the newest light boards before the 2.0 system. I would say 80% or more of the light problems I've seen/heard of are ECLE early run games, and ALL the lockup problems are on the ECLEs.
You're fine with a RR, most likely.