Peter, I'd be interested to know why you're asking? I did not have them on my 07 reg +4 and it was not a problem. But on my 18 reg +4 the brakes are just awful in heavy rain. Something I've got to fix this winter. I might just drill the discs as this has worked on other cars but I also need to contact some of the suppliers to see what they have on offer.
Cheers
John
Apologies to Peter for not realising what he needed (assumed caliper piston dust covers

).
When I first queried heavy rain brake delay I was told it's a recognised issue with wire wheels and less so with ally option. The spokes act like blades of a fan blowing surface water onto the discs and necessitating regular dabs on the brakes to keep them dryish. Not sure how effective a brake shield would be in the circumstances.
I found a change of pads (greenstuff) made a significant improvement to initial bite and left it at that.