They feel the hardest to use for me, but whenever i come up against a sniper they always seem to be able to kill me first despite me landing bullets on them so they should be flinching like crazy, but nope, I'm dead.
I tried a sniper last night (drakon) and my experience was the same as yours, I then went back to levelling the Sheiva and I landed two shots on a sniper and bang I was dead after one hit!
The shotguns, especially the argus and brecci are ridiculous.
I think a lot of the issues relate to lag, which was so bad in my last game last night I was putting 7 shots from the Sheiva into people and they were then killing me!!!!