Agreed. I have a Topeak bag and rack. One of my panniers in the bag ripped, and the trunk space alone often doesn't hold everything I need to carry, so I plan on upgrading to a larger size. I like the fold out panniers for occasional use, but having them deployed negates the easy-on, easy-off nature of the bag, so when the bag stopped being sufficient for most trips without deploying the panniers, I stopped using it. Fortunately it was easy enough to slide on the Topeak basket. Now I throw a regular shoulder bag in the basket and usually just leave the basket on, but it has the same easy attachment system, so if it's full of stuff I want to take with me, I just take the whole thing with me.

The other change I made was to change the regular rack for the Super Tourist DX, which has a 2nd, lower top rail. This makes it lots easier to use regular panniers or my grocery bag panniers and still use the top of the rack. And when I'm doing a short tour or overnight trip, the Topeak accessories stay behind, but the rack works fine as a touring rack. The Topeak rack has turned out to be one of my more versatile bike purchases.