I would say no based upon my experience with the topic below:
http://apps.magicjudges.org/forum/topic/28732/

Even though you are two judges, you are the de facto required judge, and ever since L2 became defined as the Comp. REL judge, I wouldn't let the L1 handle the event mostly by him/herself.

There was no appeals, but are you certain that every call was handled right? In my experience, players are reluctant to appeal if they are not sure themselves, and being unsure is what made them make the judgecall in the first place.

That is all good advice. I will bring this information back to my bosses and tell them they need a different staff member to work the register while I judge.

It's hard to tell the guy who signs your paycheck “nope, can't do that” without some outside opinions. I had the same worries that most of you had (Am I able to do my HJ job at 100%, what if a DQ comes up, and how do I pick between customer and player) so knowing that most other judges agreed with my theory gives me data to tell them sorry.

If the HJ isn't in the room for most of the tournament, how is it a legal PPTQ? An L2 HJ is the requirement WOTC puts on an Advanced store to run a PPTQ, and while I applaud your use of at least one FJ, you're doing him/her a disservice by not observing calls, providing timely feedback, showing players your involvement, etc.

Michael I'd also like to emphasize Jim's arguments, especially the one about separating the store from DQ and GL related feel-bads. It's ultimately a customer service issue, but the dynamics can make it tough. Bringing in a separate judging staff means players are less likely to feel as if the customer/retailer relationship will affect penalties and investigations. This is not to call you into question, but rather to point out that players may have concerns even if they don't voice them.

To reiterate what others have said:

Good idea: L2 HJ sits down in an easily accessible, line-of-sight location to work on other things. L1 handles everything other than appeals/GLs, HJ is able to observe and provide useful feedback throughout.

Very, Very Bad idea: L2 HJ is in another room. Please never do this.