A few years ago, I saw the two together as a duo. Kate, tiny but pretty and with the *best* tits. Niki, as described - just so, so. But both were decent girls, and helped me to a couple of memorable finales.
The duo bit wasn't great - far from hardcore girl-on-girl action (ooh look, our tongues touched - phwoar eh, eh? kind of thing). However they were the bargain of a lifetime - one of them failed to show on a previous visit, so they did me an hour for 70 quid.