Jury is still out on what to use but I am still leaning towards GIVI. Not sure why, just seems like a difference and good price.
I had a Givi V46 mounted on my 06 GS ADV. It worked fine - the airflow over the stock GS ADV windscreen would hit the case, making the bike handle rougher, with rear buffetting, when the V46 was on. It was something I would notice, but I could still ride the bike as fast as I wanted. It is particularly easy to remove from the bike when you want to.
I only used the V46 whan my wife was on the back because she likes a backrest. On the few long distance trips we took together, we were a little cramped for storage space between the Jesse bags and the V46 - if I was going to do much 2up touring with the top case I would have gotten the 52L for extra capacity, but for around town and weekend use, the V46 was fine.
I think Givi makes the best looking top case, YMMV.
Thanks, BobFV1, that looks great and will probably be used only with the wife on trips also. Now, I must get her approval and I can order on.