Using the Leader as the 'level' of a player seems inaccurate. When my Leader achieved level 50 my other survivors were still level 40. There's a discernible difference between Level 50 + 9 Level 40's and 10 x Level 50. It would be more accurate to make the Player level the AVERAGE of all Survivors, after there are 10 Survivors. One decimal places would be accurate enough.
For example my Survivors are: Leader 50, Medic 48, 2 x Fighter 46, 4 x Scavenger 47, Recon 47, Engineer 47, which would be 47.2 when averaged. There would need to be some minor tweaking to the Raid rules, like the ability to attack players below one's level, by at least 3 or 4 levels.
(I'm just bored waiting for my Survivors to return,,,)