I have those panniers and like them. They are small and form a one-piece unit, so they are easy to put on and take off. I don't actually use them for commuting (though they would be fine for that), I use them for small day trips. I don't think I've seen any smaller than that, so since small is what you want, I recommend that you get them.
How badly does the build up of the road debris and such build up on thr material of the panniers? I was thinking of getting that 6L x 2 one piece for my training rides to keep tools, first air, etc on the rack then in the pockets of the pants.
Also what material is the pannie made out of? Is there any rain/stain protection spray applied on it?
BTW how well does silicone spray work on panniers in general? WIll the silicone spray lessen the effects of the reflectors on the pannier by making them foggy or something?
Thanks.