snakdoc, welcome to SMF.
The reason folks are suggesting starting with a less expensive meat option is because you will be going through a learning curve. There's not only the procedural learning curve, but also learning your particular smoker...including its strengths and weaknesses. Start by getting yourself a couple of decent quality thermometers, calibrate them, and test your heat variance across the cooking chamber. You will find that particular style of smoker to be considerably hotter at the firebox end. For even cooking of multiple pieces of meat, you might need to rearrange the meat periodically so as not to overcook one and undercook others.
Vertical rib racks, IMHO, are nice only if you need to pack more racks into your smoker than it can handle if laid horizontally. I prefer the flavor and juiciness of ribs laid out on the grates with the bone side down. I believe this helps the rendered fat to baste the meat better than if it is allowed to run off quickly as it would in the vertical racks.
There are plenty of threads on here with terrific advice on preparing successful ribs. If you haven't already, browse those threads and you'll be on your way to excellent ribs in no time.
Good luck with those ribs and have fun!