Yeah, I’ve been using the 1D microcode for my X5650 as well for a while. But I wonder if we will get even a newer one soon which will mitigate the Intel security flaw which made the news yesterday. 
By the way, the just released Windows 10 fix does not use the PCID optimization on my Westmere CPU even though Westmere introduced this feature. 
Let’s hope that Intel will deal with older systems als well, but this all makes me more likely to switch back to AMD for my next build.