Rather than deleting all chests every X number of deaths, this option would allow free creation of new chests as long as a limit has not been reached. When the limit is reached, the oldest chest is destroyed. Each chest has a death timestamp (at least at time of creation), so calculating oldest should not be difficult.

I do not currently need an option that allows different user groups to have different amounts, although with the future in mind, some users may enjoy this feature. I'm not sure if the permissions you supports allows for info nodes (I use PermissionsBukkit, and will be transitioning to PEX at a later time)

kids in my server are using /suicide to build a tower of chests in the spawn -.-