Is there anything wrong with using the old orange super tuner pro? there’s plenty of new ones still for sale.
I have not used a FP3, But have run a Thundermax for 4 years and love it (I wanted the Autotune function and the ability to support a turbo)
Regardless of what you buy, make sure you get the Autotune option where the unit uses wideband O2 sensors and then self tunes to a target AF setting. Save a LOT of money on Dyno Tunes and gets you about 99% to perfect.
Other than that they are ALL pretty much the same thing when push comes shove.
I too have a Thundermax. Best thing imo but expensive. I was lucky and got mine new on gumtree for $250. Bike runs top notch. And no dyno
If you can get one and the build is not too radical they work pretty good, I'm using one at present, combined with MyTune you can get a decent DIY tune with it, you don't have to use MyTune it just makes it easier for timing, get better results with a decent dyno tuner of course but doable to a reasonable standard.