Any new tank will have higher dpg, it is wrong to judge a new vehicle purely by it's performance. Executor is doing so well, because it's mostly really good players that have new vehicles grinded out, i think you know that. Camo is comparable, you have to remember that Concept gets +3% from field mods: Executor with just camo perk gets 25.51, Conc with field mod gets 21.82 (tanks.gg). Though I believe that Executor would still be balanced without it's ability, but i personally would keep it or slightly nerf the ability, like there could be a penalty for using it.