You will probably miss the extra pen from spriggans + noxious breath in single target boss fights.

Unlike penetration does the weapon power also buff your healing, keep that in mind.

If you want penetration (cue Beavis and Butthead) I prefer TFS over Spriggans for vMA. More crit and more penetration if you can maintain the stack. Can run either Hundlings or VO body pieces with it, depending on your sustain.

I prefer to run Hundlings + VO weapons/jewelry and Noxious Breath. Noxious Breath is a nice boost and as @Protossyder said, you get poison damage, and it gives you the major fracture of NMG. But VO is the key. You get the weapon crit NMG gives, you gain Minor Slayer, you keep the weapon damage from NMG and gain a sustain and gain a stamina cost reduction on the 5th piece (on both bars if you don't have the vMA bow and are running a VO bow on the back). You could run TFS with VO if you want the most penetration possible, but Hundlings is better for the weapon damage/crit output

I guess TFS, VO and Relequen aren't an option, when OP says "outside of trials" .

I would keep Noxious Breath on the bar. Hunding's + Spriggan's is solid. IMO there won't be a huge difference to Briarheart, Veiled Heritance etc. If you have Spriggan's and Hunding's golded out I wouldn't bother for another set except those from trials. Except you are having sustain troubles even with Dubious Camoran Throne. In that case I would give Bone Pirate's Tatters a try. You can use it for PVP, too, so it wouldn't be wasted if it doesn't work for you in vma.