Welcome Steve, another Darkside is always welcome.
As someone who has kats with 19" front wheels and a couple of pop up kats with 16", I always find the 16 seems more "unstable - (twitchy)" than the 19, but that feeling goes after a few kms and then its all fine. The 19 when I get back on then feels slow and lumbering, again only until I adjust again, I agree with John that there isn't anything wrong with the 16" once you get used to the feel, it is different, but there is nothing wrong with it, just takes some time, especially if you have spent a lot of time on another bike. My 5 cents worth anyway, Cheers and welcome again