Dave, I changed mine to Halycon backplate but I kinda like the JJ webings as I can adjust them to get in and out of it easily so I replaced the original Halycon webings with the JJs. Very small difference in the Vees... very minor.
I was gonna ask that question also as my JJ is too negative for tropical water diving. I'll use my ali Halcyon plate but with my JJ harness.
Think I met you in Gili Edward?