Questions about checksum feature in 9.3

I am getting a new server ready for production and saw the release note on the new checksum feature. I thought it
soundedlike something we might want, and then after reading realized we have to initdb with the feature on. I figured
I'dbetter check into it a little more since changing later might be a bit of a hassle and found notes on getting a
vectorizedversion running for better performance. 

My attempts to compile it vectorized on OS X seemed to have failed since I don't find a vector instruction in the .o
fileeven though the options -msse4.1 -funroll-loops -ftree-vectorize should be supported according to the man page for
Apple'sllvm-gcc. 

So, has anyone compiled checksum vectorized on OS X? Are there any performance data that would indicate whether or not
Ishould worry with this in the first place?  

So far we are pretty happy with the performance of 9.2.4, but have noticed a few situations where it's a little slower
thanwe might like, but these instances are rare. I'd accept a small performance hit if we can get better reliability
andawareness of potential problems. 

Thanks,
Kevin