As far as I remember Match himself didn’t trust his Vf measurements (whereas his lumen recording seemed pretty accurate and I regularly rely to his charts).
When djozz did his “crash testing” he stated Vf as well and had 3.55V at 3A for an XP-G2. That sounded very reasonable - and is higher than XM-L2 with 3.4V at 3A and much higher than an XM-L, which seems to have a Vf of 3.15-3.20 at 3A. Here is the post of djozz with the graphs for XM-L2 and XP-G2.