When I bought my first Concours back in '99, I bought a Givi trunk and figured I'd use either the trunk or the panniers for normal everyday, around town useage.
Ha! The trunk never came off. Neither did the panniers.
It's nice to have a choice of which kind of storage you want to use. With the Connie, I used the same strategy I use with the NT: tools, road stuff, different gloves, etc. all went in the right pannier. I had the trunk and the left pannier (and the pillion available for the carriage of ... stuff. My personal best for amount of groceries carried on the bike was $274. I've only made it to $240 with the NT (I do have the big lids, BTW).