What type of vehicle would you be carrying your roaster in? Is it going to be a trunk monkey? Given the amount you want to roast, a gas one would be pretty heavy for that. You'd want it in a trailer. The Artisan though, actually could do 7 lbs and you could pick it up. it'd fit in a trunk it's a box really so not like there's a lot of pipes and hoses to bust off. You could put it and / or the generator on a wheel dolly, carry it around in a 5 x 8 enclosed trailer that you tow behind your car / truck. I think it'd be very workable. As a plus if you could find yourself somewhere where there is electricity available you could plug in and not have to run the generator.
The Artisan would do as little as a pound. They say half a pound but it can get finicky, id go with a pound and up to 9 with the Artisan 9. Smells are definately there, and the site too, you can look right into the chamber and see the beans bouncing around, see the chaff wafting out, smell the smoke of the beans going through the nutty stage, and the roasting stage. A drum roaster that might be all enclosed and not much to see really, until you get to where you pour them out to cool. Though if you wanted, i am sure you could get a gene cafe or something like that solely for the 'show off' affect.
Aaron