I also didn’t order the side pannier bags, I kind of wish I did now. ...
I wouldn't bother with the side panier bags - they are not waterproof as a certain person found out in Grindelwald...and they collect debris/water on the top flap part unless the panier is packed full.
I would order the side luggage carriers, but use them to attach standard motorbike waterproof bags usiing bungees. The "designer panier bags" and suitcases dont look especially waterproof... Hmmm I wonder if a bag would attach on the side above the exhaust using bungees on the M3W? Something to experiment with