I've picked up a lot of great smoking tips by going through the site, and when I read this thread I felt it was my duty to reply. I've been in bourbon exploration mode for the last 8 months and topcop I hate to say it but your liquor guy did you wrong. Ezra isn't bad for a mixed drink if you're going to overpower the flavor but it is not fine whiskey by any stretch. It won't give you any of the flavors a good whiskey will impart to your sauce: oakiness, toffee or vanilla notes. If you want something that doesn't have a top shelf price I would recommend Buffalo Trace, Elijah Craig, Bulleit. Those are all good enough to stip in my opinion, and if I won't sip it I won't put it in my sauce.
Jack and Jim are good brands but are most known because they've successfully been marketed. I would put Woodford Reserve over either of them but you'll pay for it too. Especially the double-oaked batch.
Just FYI - Jack Daniels isn't called a bourbon because it's filtered through maple wood charcoal before it's barreled for aging but other than that it adheres to all of the bourbon rules.
Thank you all for the contributions you've made here. I'm smoking 30lbs each of pork shoulders and briskets for my son's high school graduation in 2 weeks and I wouldn't have felt ready to do it without all of your help. And my friends and family have loved the trial runs the past 2 months.