Are Basil Panniers stable on the rack?

I'm looking for a nice looking pannier that I can use to do the following:

1. Bike to work, which means packing my laptop and taking it with me as well.
2. Bike to my local grocer to buy some items every so often.

I like the look of the Basil Grand, and it seems to work for both use cases. However, it looks like it only has a single attachment mechanism at the top of the bag. No security straps or hooks at the bottom.

Does anyone own any Basil bags? Is the Basil system stable on the rack?