Truthfully, due to NPC eagles and other small craft actually staying on your bumhole (like they should I mean them sitting there and barreling was really bad) anything as large or more than a python needs them just to land hits. But the problem is in my bug post linked above. They don't track consistently and c3's don't track at all as well as dmg being absolutely stupid low on the rare hit with e'm. C2 and 3 track much more effectively than 3's but still bug out a lot. More on DMG; watched an eagle in a CZ sit on my nose for for about 5 seconds, eating all my turret fire because they decided to work right for a short time, and in those 5-6 seconds not only did it reduce my A-battle-conda to 17% hull from full shields (4 pips to sys) it also barely lost one ring of shields itself. They were 4C3's, 2C2's, and 2C1 pulse turrets and this is what I mean by them being not viable.
You can get some hits with them depending but you cant rely on them for anything other than to disappoint you.