What are the Formulas like to bleed?
And are spares as difficult to find as people say?
Notoriously bad. The lever is a haven for trapped air, and they require bleeding perfection to remove as much 'sponge' from the lever feel as possible.
Personally, I ran some Formula The Ones's for 18 months & had a general all round crap time with them. I will stick up for them and say freshly bled, with fresh pads in, they were great. However, lever throw is massively affected by pad wear, they pump up no end, they eat pads like a fat kid loves cake, etc etc.
I a had an entire replacement set from Propel to combat the 'issues' I had, but they were exactly the same, so I sold them. Been running some Hope Tech M4's since & they have been like night & day in comparison. The lever throw is consistent to pad wear, the adjusters actually adjust, and the power, although not as strong as a freshly padded/bled Formula, is much more consistent overall.