It's risky. IAC has a standard, no sublease policy...you qualified for that apartment and received those terms based on your credit/financial situation. They won't allow a substitution. If you include IAC in the process you are going "rent responsible." Many properties offer this option which essentially allows you to move out and you're off the hook once your apartment is rented out to another it doesn't matter if IAC finds the new renter or you bring one yourself). The hitch is, IAC will expect a new (likely 12mo+) lease and the pricing is controlled by them (who knows some managers may go along with allowing your terms to stand if you bring the new lessee...i imagine this to be a longshot though). Subleasing would have to be done behind IAC's back...which is what the rest of this post assumes:
So if you are the person offering your home to someone else, you are breaching your agreement. Also, you have to consider how the actions of your "tenant" will affect you. If I were a less scrupulous person I would take you up on your offer, move into your apartment, and leave with all the appliances, fixtures, and anything else I could tear out of the place over a period of a few weeks. Try explaining to the IAC lawyers why you shouldn't have to pay for all the damages resulting from your breach of contract...and you know there are some real scumbags out there looking for these opportunities.
If you are the individual moving into someone else's IAC unit, it's less risky...but headaches still exist. Whenever you seek any interaction with the office or maintenance staff, you have to pretend to be the person on the lease. If IAC becomes aware of any utilities changing over in the name of someone not in the lease, they may require explanation.
I'm curious what one would do if the person whose name is on the lease lets you move in all your items and then has IAC change the locks while you're at work? Or what if you just move in and then are robbed the following week? You have no idea who has a set of keys to that place. How would you take care of the security deposit issue if you are taking over someone's lease? Would you cut them a check for the amount of security IAC has on hand from them? That sounds risky.
In my opinion, no matter which party you are, the potential for disaster is too great. But you'd have to do the cost/benefit analysis for yourself.