The downside to optimized ECP is that it only comes with Gunrunner's Arsenal so the actual thing 5mm JSP ammo should be compared to is max charge ECP.
5mm JSP is a GRA ammo type so no, JSP should be compared to optimized ECP.
Max charge ECP does give a bit of extra damage, but it degrades the weapon a lot quicker then 5mm JSP ammo.
It also does more damage and negates the same amount of DT. Whether that's worth the condition penalty is up to you.
It actually sounds to me like the Gatling Laser needs all of those perks and the completion of Lonesome Road in order to be comparable to the CZ57 Avenger. That's my opinion at least, I've always been a guns man myself.
Incorrect. With all the perks the Gatling Laser does substantially more base damage and dps than the Avenger (not taking into account crits, which pushes the GL even further ahead). It's only with AP ammo against heavily armored foes that the Avenger wins. This isn't a matter of opinion, the numbers are clear:
GL base damage: 13
Chance to crit with light touch + laser commander + set lasers for fun = 19% (we can safely ignore the stuff that gets added in before the crit multiplier since it becomes negligible with the automatic weapons penalty).
GL crit damage with better criticals: 15
Total damage before perks + ammo: 15.85
Total damage with laser commander + optimized ECP + Camarader-E: (15.85+5)*1.15*1.3 = 31.17 (I'm not sure if additive bonuses get added before multiplicative ones, but it shouldn't make much difference either way in this case)
Total dps:
935Avenger base damage: 13
Chance to crit with light touch: 5%
Avenger crit damage w. better criticals: 19.5
Total damage before perks + ammo: 13.98
Total damage w. 5mm JSP: 18.17
Total dps:
545.1