Thanks Elnino and Hoss22.
I ended up buying a 169g GL and a 173g Opto (both production run). The Opto is obviously the more OS of the two, but they fly pretty similar. For RHBH they fly more OS and shorter than the Nuke OS. For thumbers they flipped faster in the air and went a shorter distance. They were easier to control though.
I tested several other discs for thumbers and the Firebird is still better than anything I have for pure distance, followed by the xXx, then Nuke OS, then Stiletto. The Nuke Os got the boot and the 169g GL Stiletto has a home in my bag now.
The Stiletto was crazy good for forehand rollers BTW. :thmbup: