The Combat Janitor is basically a suppression and clean up mech. It plays pretty far back in the battle and fires away with the 2 AC\5. It has one JumpJet to help get over steep terrain and for sniping shots. When a battle is nearing its end, it moves up and puts the 3MLAS to use with the left over AC/5 ammo.
Personally, I'd drop one of the arm MLases (or a ton of AC/5 ammo) and put in two more JJs. There are situations that a 'mech should never get into and a jump capacity of 3 will get you out of several of those.
Another option would be to scavenge an XL210 from a commando and do this: Not that jump capacity that I prefer, but enough to comfortably get you up some of those pesky barriers.
Liked your build overall, and a friend was thinking of tossing 2x AC5s on his BJ. Drop the engine to a 200XL and toss on an AMS. 72 speed down from 79 is doable, and I'm not running anything without AMS these days.
