If you rode dirt, you Have ridden motorcycles..
Excellent choice, a 125 is really too small for streets. If you have hesitations, spend $400 more for an MSF class. Good investment, you might get a CC class and Pell grant so cost to you is $50. Epidermis is $$.
EDIT: A Middle sized Honda, is a 600-650. A mid sized Harley is 88 cubic inch. I dare anyone to ride a 300 coast to coast like in "Zen and the Art of Motorcycle Maintenance." You will pull over a Lot. Big trucks will Suck you off the road. Just because a 125 and bigger is "legal" for freeway does NOT make it any good for it for Very Long..
I started on a moped, then Honda 50, 70, and 90 ; then a 650cc Triumph. No classes, then, but I learned. Bigger bikes are actually safer.