It must be asked, stab incidence relative to what?

If it refers to the stock location for the stab "saddle" in the fuse or the stab incidence relative to the canopy rails, then those really don't have much meaning because what is really important is the wing/stab relationship.

My suggestion is to assemble the plane "box stock," getting everything as squared up and straight as you can, with CG at the suggestet 120mm. The plane is definitely flyable in this configuration, if not (IMHO) nearly as good as it can be.

Both the ones I have assembled - as I have mentioned before - flew with a funky nose-high attitude, needed a lot of down elevator trim, needed a ton of down elevator to fly inverted and were a handful to land. The wing incidence mod erased all these characteristics.

That said, some guys seem to be happy with the way the plane flies with no modification. I can't know if perhaps Phoenix tweaked it a bit at the factory, but this is possible. Recently an older gentleman at my local field got one and I noticed that the canopy attachment has been changed a little, using two tabs in front captured in slots and two canopy bolts in the rear, so I can only wonder what else they might have done. He hasn't flown it yet due to recent cataract surgery, so I don't know yet how it flies.

Bottom line is, assemble it stock and see how it flies. If you think you need the wing mod, it is dead simple to do and would take about 20 minutes tops as a field repair.