I think you got the wrong idea when i said ambushing though i can see how you might of thought that. For me, pretty much any medium/light falls into this. You don't push out huge DPS, or alpha's so your best bet is to pick your points of attack and go all out before you disengage, My main form of "ambush" is wait for a mech to engage another mech, and then attack back armor, or do a strafing run on a weakened target.
Dodge/wade through the battle field taking some pot shots hoping you can distract mechs, mostly in the case of lights, before you run being cover hoping you distract enough, or get someone to chase even for 20 secs, which in this game 20 secs can = death.. Or where the 4G shines i tend to try to sneak in from behind and wreck an assault, before you disappear as he turns because his back armor just went from no damage to bright red with cockpit reading "critical hit", Hopefully, either he doesn't turn and you finish him, or he does turn because he is dead if he doesn't and your buddies get shots of a freshly opened backside and he is dead anyway.
The other option is finish off a medium/heavy that has got an open torso, or take out a dangerous weaponsystem stuffed in a side torso or arm. Of course I'm targeting mechs, that other teamates are working on but that should be a given outside of points of opportunity. . Often they can be wrecked enough that just a couple well placed AC-20 shots can take it down. But even still, it takes 6 shots from an AC-20 to take down an assault outside of the rear and that is if they hit the same spot all 6 times Or even 3-5+ shots to take off a dangerous arm for example say for example a dragon 1N and it's dual AC-5's you basically destroyed their damage capability... you are just using to much of your total % of ammo for my tastes is all especially when the 4p, Can alpha higher and basically put out the exact same DPS as the 4G. the one place the 4G does out shine is it is pin-point. But as far as Decks goes i just can't help think in CW, When i do drop with the 4G in one slot, typically a middle slot, and it just ran out of ammo too fast..
For me, if i wan't an AC-20 in cw, id run a misery, or a cataphract, as then can hold 35-42 shots.. verse what i run in my 4G, of 21. Like i was saying, i love the 4G in fact way more than the 4P. which is my least favorite energy boat that i own so is kind of ironic that i am saying take the 4P over the 4G but yet hear i am. Typically in a game i get between 250-400 damage and 2-4 kills and 3-6 assists. In fact, my kill to damage ratio on this mech is higher than any other mech i own, though my t-bolt 5SS has a higher KDR and over all average damage but as a short range murder machine, it is hard to beat a 4G.
If i want an ac-20 in my drop deck which for me, is Yes i do! this is the one i am working on getting the extra modules to run all 4-- (i got enough modules to swap around so i know what they all have, i just need a few more extra so i can keep the deck ready while i play my other mechs)
Deck,
1, Misery, ac-20+srm 6 + a pair of LL's
2, Dragon 5N, Gauss+2 ERLL's
3, cicada, Ac-5 + 4 ML's and ecm
4, TDR-5SS, 5 MPL's+ 2 ERLL's
But hey, if the 4G and 4SP are working for you, right on. It is nice to know a little in-site on how it can work as you are talking about a couple of my favorite mechs, and 2 of which are the first mechs i played after i did 100 drops in a trail dragon 1N