OK so here's the follow-up story:
Issue 1: Wilwood caliper is shit. Flexes too much.
Issue 2: The workshop who first did the brake work did a complete naff job. Caliper was grossly mis-aligned on the rotor. To the point that it was pushing the floating rotor off straight. Spacers they made for fitting the caliper were made of aluminium, which had deformed. Spacers weren't even identical size, meaning, one was torqued more than the other when fastened. Didn't space with washers. Used stainless steel bolts to mount caliper. 11/16 Dual disc M/C was oversize. And needed to be rebuilt, as the piston wasn't fully retracting, but wasnt. Due to caliper mis-alignment, the caliper housing was CONSTANTLY fouling the rotor. Its actually embarrassing and offensive the work they did.
Fix: Went to another workshop. Fitted new HHI 6-piston. Fitted 9/16 M/C. Fitted new brake-line and better quality fittings. Proper spacing and alignment of caliper on rotor. Made sure it worked as expected.
Result: A performance brake setup that works better than factory, as it should, not worse.
What I learnt: Wilwood calipers are shit. Rosnar Motorcycles do great work, above and beyond expectation.
Good story BBYHD, look's nice.
Thanks for the tip!