Wired Intelligent Edge

Other than price, what is the difference between a HP Genuine SFP+ (J9151) ~$2,100 vs a Axiom or Transition SFP+ (~$700)?

We have both, but other than price, both perform the same. 

I believe the HP Genuine SFP+ comes with a lifetime warranty, but for the price, my gosh!

If you use Procurve switches, you'll have to make sure the non-HP SFP+ is coded with the J9151 part number correctly.

Another factor is that HP will not support your configuration and will ask you to remove the third party transceiver before starting with any troubleshooting if you encounter any issues.