I would not leave the airport. The Delhi lounge was actually pretty good (relative to other lounges in Indian airports), quiet and comfy.

If you decide to leave, remember you need a paper copy of the ticket to get back into the airport. Electronic copies are no good. And it won't be a quick process, normally multiple sets of security all with pat downs on every pax.
Plus you have to deal with Indian traffic which is somewhat unreliable.

And my favorite at Delhi airport, getting to the gate and finding 300 Y pax ahead of you in a 300 person queue that takes 45 minutes to board.