When the jib boom pivot location on the boom is moved , it changes the rate at which the jib swings in and out with sheet tension. So the jib or main boom sheet attachment locations may also need to be changed to keep the jib's movement synched with the mainsail's movement as desired. Stock Nirvana sheet-boom attachment locations are fixed, so they may also need to be changed to adjustable like in the super Nirvana pic.
For more on boom/sheet geometry
Boomer, I actually read the Templus Catcus post in 2007 and put a rubber grommet on the Nirvana jib boom pivot like in the super Nirvana and RG65 pics. I never really noticed much difference when moving it around, but I wasn't trying to correct anything and probably wasn't a very good tester.