Is the Warden worth it for someone who mains Heavy/Engi?

The Warden is a weapon that you need to trial before you spend the certs or Smedshekels. It's a love it or hate it gun. There's a couple guys in my outfit that are absolute gods with the thing (they were even before they buffed it, when it was really underpowered), but a couple more that hate it. Me, I can't make it work. I'm not a good enough shot, not even close. It's a weapon that has a high skill floor and I'm still in the basement.

For a heavy, no. Equip a Godsaw and spend time learning to tapfire and plink with it, it's dominating at mid-long range (until you get sniped). For an engineer, the Warden's viable if you try it out and you "click" with it.

Odd thing is, I almost never see any TR using their battle rifle but I get shot by VS with Eidolons a surprising amount. A lot of the Mattherson VS seem to like the thing and are very good with it.

Yes, that is at least partly because the sights are almost universally badly centered.
http://www.reddit.com/r/Planetside/comments/21qzpv/all_3d_optics_are_misaligned_view_full_size/

Here's the VS gallery and yes the center of the screen is below the entirety of the oversize dot:
http://imgur.com/a/P4fkR

My advice is to practice endlessly with this counter intuitive set up until you have completely mastered it. Then maybe Sony will fix it for the rest of us.