I think it's important not to pigeon hole yourself into certain weapons or types of playstyle in Warframe. This is MY opinion on this, as I have a friend that just wants to play Rhino and nothing else, and while that's fine for most things, there's just way better Warframes for most tasks. So quite often I'll have to carry his arse through a mission, or get half the loot, or it takes twice as long as it should -- but so long as he can ground stomp and rezz me after I've fucked up and died, he thinks that's a reasonable trade-off. It's fucking infuriating at times.
Always, always pick the tool for the job, as your arsenal increases that toolbox gets bigger, and lets you take more risks. If you're planning on getting a mission DONE, don't fuck around and bring a level 16 Oberon to the Plague Star 4* boss, get the best shit you got for the mission and knock it out. Grinding out mastery weapons should be done with at least one other weapon you have that can kick the crap out of The Stalker at the minimum. Sure, you can void this by making sure you have a pre-made group that capable of killing everything for you, but if you're going to pug a mission, even for XP at least bring something to the table that gets the job done.
At the moment I'm running Plague Star as a Pilfering Hydroid, I'm using my tricked out AKstillettos for general kick-assery and boss slaying. While Hydroid isn't exactly slaying hordes of infested, he is at least crowd controlling a few... plus with PF, the bosses are dropping way more loot.
PS: Vorph, why would you ever bring more than one Nekros to a fight? I've long believed that Desecrate destroyed the body on activation, and thus multiple Nekros would only serve to cover more area, not produce more loot. That was back in the day that Nekros had to actively spam Desecrate everytime a bunch of shit died.