Hey Alex, how did you end up going?

I did a tonne of reading on Opticoat and people's reviews, eventually convinced myself it was worthwhile after stumbling on this link (for those of you interested, follow David Fermani on pages 1, 2, 7 and 12):
GRAND FINALE -Optimum Opti-Coating - Durability Test Review!!! - Car Detailing Product Discussion - Autopia

I recently Opticoated my car, windows and alloys. I specifically wanted the alloys done as I wanted to be able to easily wash off the brake dust, which builds up ridiculously quickly!

So far I'm very happy with Opticoat, the treated surfaces bead and sheet water very nicely. The brake dust washes off easily but as you'll see in the video there is a faint layer of residual brake dust, you can see my finger swipe on the 2nd wheel at the 3 O'clock position. A a final spray with QD/equivalent product and a wipe down with a microfibre towel will fully return the alloys to their former glory.

Washing Opticoated wheels - YouTube