I have a "mint" ST Concert Solid Top that I'm considering selling. Once you've decided which one you want, send me a PM and we can work out a price. It's strung with Worth Browns and in a Romero canvas/solid foam case. I've owned it for about 6 months, and, although I love the sound and playability, I've found that I'm not playing it anymore. (I've received two new ukes since and they are getting all the attention.)
FWIW, I highly encourage you to -somehow- get any one of them to play. Not so much for the tonal questions, but how it feels to you. I've noticed that my left hand bumps the "A" tuner when playing cords around the first/upper frets. The distance from the tuner to the nut and first fret is much closer than on my other concerts and tenors. You'll only know if it bothers YOU if you can hold and play one. For me it was a minor annoyance for what is otherwise a fabulous uke.