There will be no such thing. Please don't start messing with two different systems at once Square, enforce using one system and make it great instead of trying to cater to both.Please find the right balance between the 2 (Now I'm not saying to nerf SP from leves, just improve SP in regular groups) so that regular parties are encouraged more..
People will not be happy until both systems are equal/one is better than the other, at which point the fans of the other system will complain. This will go on forever if you don't put a stop to it, because you can not make the systems equal with so many variations and factors to take into account.
If you ever implement a harsher death penalty you fail as developers. Make the fights challenging instead.1) You don't loss sp when you die.