I came to love my 4X and now play it more than my 3L. I went the focused role route and equiped 2x AC/2s. Stripped off the right arm armor, no JJ's (I know, crazy) to make room for more ammo. Then I paint in battleship gray so it doesn't stand out.
It's just this little, non-assuming, non-ECM mech that isn't throwing out big beams or light balls to draw attention, sitting behind cover and a line of bigger mechs.
Both the AC/2s are mounted high and on the left side. Perfect for hull-down firing. Even if your cover is the friendly stalker in front of you. But, most assault pilots don't mind when suddenly you you go Chainsaw mode on their target and rip holes in them. It's no guarantee by any means, but I can regularly rack up 400 some-odd damage in a round with kills. Typically against bigger mechs.
Worst case is getting jumped by a pair of enemy light mechs. But, it's 2 against 1, you'd be hosed if all you had were medium lasers and Streaks too. Even one can be a threat; but I've gotten good enough that I can land bursts of AC/2 on a circling light inside 50 meters. A few solid hits and most will peel off for cover.
Pro-tip: You ammo is limited and once it's gone, your nothing more than a moving target. Don't go chasing long-range, low percentage shots. Wait, be patient, and light into someone when they aren't paying attention to you and already in an exchange with another mech. Close enough that you can be sure to put each round into the same location to tear through quick.