To me the Balius E seems almost like the beginner's variant or the one with training wheels you give to a new guy. When the Balius first went into production they were handbuilt or low production runs. It was only given to high ranking warriors with bloodnames, i.e. warriors who had proven themselves in combat many times over. They knew how to make the most of the limits of the various Balius variants.
The Balius E appears to be from a time when the Balius is more widespread and given to less skilled, less capable warriors. The weapons (ER Large Pulse Laser, Streak LRM15, Streak SRM 6, Improved Heavy Medium Laser) all sacrifice weight (or gain explosive properties) to improve the targeting performance of the weapons. In addition, due to the streak missile systems it is very difficult to overheat the Balius E using the forward-facing weapons, unlike most every other Balius variant, meaning it is more controlled for a new warrior.
That said it is not a bad 'Mech, it can deal a 10-point hit at long ranges and crit seek with missiles, it's just a bit plain in my eyes.