Info pass should work if things work out fine at USCIS office, ideal conditions.
One drawback is there is no walk-in. If you say emergency..., emergency is to you not for the security person..., so he will not let you upto the counter.
Also, the website is designed to give you appointment only after TWO weeks from the date you get into InfoPass website. In anycase, you will not be issued appointments earlier than 2 weeks.
I bet, it will be 100 more years, before at least one person says the service at USCIS offices... is good.