Quote Originally Posted by Unregistered View Post
At high enough base attack, you'd probably still want an SR with assault over the SSR with defender in the theoretical lategame. For an SR, lv 20 assault adds +13% to the character side of the damage formula. The event SSR with defender may have a 500-700 point lead over the prison raid gun at max, but it won't contribute to multiplying the attack given by everything else you're using.
You're ignoring the fact that extra HP isn't worthless. It allows you to heal more efficiently and use a more offensive team composition. That said, you'll generally get more mileage out of an HP/character ATK eidolon.