I think the common misperception for players that start using stealth classes are that they go in with the expectation of being able to steal the off node. This is certainly fine especially if you know what you are doing. As for me, if I can draw 2-3 people to their of node and give my team enough time to cap the mid node or take the orbs, that's mission accomplished for me.
Also, it takes a stealther to rat out a stealther if you know how to do it. On my sin, I usually let a non-stealth bait-cap while I stay stealth. When the capper gets sapped, that is when I use my knockback to rat out the other stealth.