Even if these are all valid points, it still stands that Rebels aren't given 9.3 machine guns etc. for a reason, hey SP remember before the Altis Life remaster came out, FED was piss easy for ya'll because you all had Navid's that could tear through Hunters and Striders like a 1000 degree knife through ice cream (ridiculous right!?) that is why these changes were made to balance out the way you have to play and maneuver to win a situation like fed. Like @Magix said FED and Neri bank are a high risk high reward situation, (use big guns get big moola) without sacrificing some of these weapons that can take hours to source you are not going to succeed in robbing Fed, that was why SP is so successful, you guys don't care about money, you can just go make it back again in the old days or buy a new Navid. However now that the tables have turned and you guys have to work for these high powered rifles and machine guns, from my point of view the system is balanced as is. And as for whether rebels and cops should be allowed to log on and respond to Fed bank etc. ABSOLUTELY! After all the economy on the server it has been made for fun, trust me when i say it wouldn't be much fun to sit down in Sydney LAC or as rebel at rebel 1 while all your buddies are smashing Fed or bank etc. although i think some of the cop situations are a bit edgy when they have pulled out things that shouldn't have but after all the server was made for fun, not be be ultra realistic. That's where i think we all get caught up, yeah this might not be to real life scale but it is supposed to be fun. If you want something realistic go rob a bank IRL (just kidding don't)
To finish off i think the system is fine as it stands and doesn't need to be changes and i think everyone needs to sit back and just have fun while they are playing cop or rebel and doing Fed or bank. Lose a lynx? WHO CARES after all its a game and everything can be regained and like i said Fed and bank are high risk high reward, if you aren't going to put effort or money and big guns into doing it you are not going to succeed.