Heya, sorry for the delay in replying. True-Fi includes three profiles: headphones off, ANC on, and Ambient Mode on. After a few days of primarily using ANC on, I'm pretty impressed. It really does tame the lower end of the XM3's stock signature, and its volume limiting/pre-amp function on macOS is a nice touch which makes the XM3 pair even better with my DragonFly Red. I still slightly prefer the extra bit of air and treble sparkle that the Radsone player's EQ provides by comparison, but in truth, both that player and True-Fi provide excellent ways to bring out the best in these headphones. It really is a shame that Sony put these on the shelf with their stock signature, because once you 'correct' for that by EQ-ing your source properly, these really become excellent mid-tier all-rounders. The midrange is just so clear once the bass is dialed back.
So yeah, True-Fi makes a very positive difference for the XM3, and the three profiles they've included should provide a lot of versatility depending on how you're listening. In fact, even the 'headphones off' preset helps quite a bit as well, which is impressive considering what a hot mess these headphones (well, all ANC headphones) are when they're powered off and plugged in. That said, I wouldn't expect much beyond what folks here have already attained with proper EQing, but if you carry the XM3 around with you, it's always nice having another easy way to get the most from them.
Also, whatever issue I was noticing with the True-Fi iOS app seems to be fixed with the update from last week; it shows and plays all local music on my iPhone and iPad