I have grade 5 Aphelion and Eclipse that are pretty good all-around guns, getting through shields as if they weren't there and shredding armor reasonably well. Being not a fan of this whole gun-juggling business, I'd rather use a single gun to do the job. I know that plasma is great, and have a grade 5 Tormentor that is excellent at close range, but it's not that hot against moving targets at a distance (and don't get me started at that "sniper rifle" – after the first awe faded, it's laughable against anything but unsuspecting, unmoving targets, making it strictly an assassination, not a battlefield weapon).
Are Karma weapons at grade 5 usable against shields, or are they just as pathetic as they are at grade 2 and 3? I have a grade 3 C-44 and a grade 2 AR-50, and both are quite miserable against shielded NPC-s, and I won't bother upgrading them if they're going to be just as bad at grade 5.