I think one downside of the W2 is the reported propensity to crack. I don't know what percentage it affects, but I know it isn't an old wive's tale. I think it was fixed in the later castings? I know that I considered this when I had access to a set of early heads at a good price. I was hesitant to put all the porting work and bespoke parts into a part that had a chance of leaking. I still want a set and if I find the right vintage and configuration, I'll get them. That's another downside is knowing exactly what version you are getting. There are a lot of options and the PN's don't seem to be well defined on the heads.
