@N1Rat, while I was writing this, you've ordered the Shad

. My comments below may help others.......
I have the Givi V37 panniers and inner liners with the quick release mechanism for the frame. I only have panniers on for overnight trips and it takes 5-10 minutes to fit the frame two or three times a year. When the frames are off, one would be hard-pressed to notice the vestigial mounts that remain fixed to the machine. I have enough space in the garage to store the frames and boxes when they're off.
They're not the largest panniers, but I manage two week solo trips with them and a top-box. Like most Givi's you cannot lock or un-lock without a key, but I can put up with that for 6 weeks a year. They don't stick out as far as on some of the adventure bikes with ally boxes.
Givi supply an extra lock barrel with the V37s (and the V35's, no doubt) to enable me to recode the top-box as well as that never leaves the bike. I absolutely detest carrying my helmet around and refuse to hang it by its strap to the bike.
I was never going to cough up for the BMW 30 litre top-box, as I'm used to a 56 and 58 litre Givi's so why should I go for the BMW panniers?
Shad make some plastic panniers for BMW but not all.
I don't think one brand is better than the other when it comes to hard luggage. I might well have chosen Shad if I was not a long-time Givi user.