Jetsteamer - yes, yes, and yes! Yes you should do it, yes you'll do fine, yes there will be people in the dust with you (and in yours) with every kind of bike!
I ran the sandblast rally for the fist time earlier this year and had a great deal of fun. Enough that i have since driven 12 hours each way to go to Rally West Virginia which was even more fun.
Sandblast is a great place to start. It is basically dual sport riding at whatever pace you are comfortable with. There were nearly 40 bikes there of all types with riders of all types. The common theme being everyone is very friendly and happy to help out noobs. Trust me i know - i'm a nooooob and have gotten lots of help.
See you there!
Hey, is my collar bone supposed to look like that?