I started with a DaKine XTSeat/Reactor (roller hook), which worked fine with
the two line kite (no trim loop to take up space on the hook), & with my
"MelMods" (4-line, but still no trim LOOP). I switched later to a plain
hook (stainless Windsurfing Hawaii), but only because it had a better
attachment point for my trim line snap shackle. I chose stainless over
aluminum because I could safely bend the hook slightly to my preference,
without worrying about weakening it.
There's nearly never any need to switch harnesses just to get a different
bar, they're nearly always interchangeable. There's also no real need for a
special leash attachment point on the harness, because the clip on the end
of either of the DaKine directional leashes will clip right onto the slot in
the end of either a plain or Reactor bar. Barring that, a stainless
caribiner will also clip on there (you can tie a loop of line through the
closed Velcro cuff, or through the swivel, after removing the screw that
holds it onto the cuff).
Recently I switched to a Fusion, but I'll be going back to the XT, because
for ME the Fusion comes too high on the back (hits the bottom of my wetsuit
zipper, & I can feel it against my back) AND the front (the big, wide Velcro
waistband makes it hard to bend over to put my booties on & off).