Your nervousness may be what the psychologists refer to as cognitive dissonance. It's expensive but it's a good brand from a good retailer, it'll be fine.
The only difference is the super tenor has a wider lower bout. Same 17" scale length as a normal tenor. I really like the sound they produce, has full rich bass tones.
Congratulations JJN, The only thing to be nervous about is how your other ukes will feel when this bad boy shows up.
Congratulations! I have the exact same uke and love it. I also got mine from HMS and it arrived beautifully set up. I hope you will like yours too. P.S. I found that Living Waters strings surpass others on this uke.