Well as my close fitting NN Hugger that is on the swing arm sometimes hits the underside of the rear subframe I believe that both types of hugger / rear mud defelector can hit under full load (although I do have lowered suspension) and the only times I have had this happen are full load riding through a (compression) dip in the road dip at speed
Probably the only one that won't is the rubber car mat cut to shape and fitted immediately in front of the rear shock.
Finally put my mudsling on my factory lowered 1200gs with the rear damper on 16 clicks in and on one occosion had both wheels airborne over a bump at about 60mph.I weigh 14 stone and the mudsling didn't catch anywhere so i can give posetive feedback and am over the moon with it.
.....Also got this from the manufacturers so have just ordered mine,
Ian,
The Mudsling will not foul the tire if used with lowered suspension. It has been installed and used successfully on lowered models. We add the note in the instructions to mitigate any possible misuse by those who overload and fail to set up preload properly. In the worst case of overload with inadequate preload the right side of the Mudsling can get close to the inside of the paralever and possibly touch it. If, as you say, you won't overload and properly set up suspension, it will be just fine.