On my alt I have a level 50 GLD, never leveled up CNJ for the PLD job, either. Currently she's decked out in full Militia gear (working on penta-melding it) with Allagan belt and DL accessories, rocking and HQ Mailbreaker and HQ Darksteel Scutum. It's certainly a viable strategy for 4-mans, having run AK in it by accident once (no wipes, thankfully). It's ridiculously hard to keep aggro against people using Zenith weapons, of course, but it's not impossible. Needless to say I'd never run Coil or CT with it, haha.

Just from my experience, however, the best thing about GLD is that they're really able to make use of other DoW's abilities to boost their damage dealt and mitigate damage taken. Haymaker is great for mitigating a bit of damage with Slow (and debuffing targets who use Haste), Featherfoot and Invigorate are great additions for obvious reasons, and Second Wind's always useful in a pinch. They can also buff their damage pretty consistently with their natural Fight or Flight, alongside Raging Strikes and Blood for Blood (combined with Rampart to cut off the increased damage taken). Straight Shot allows them to always keep up an increased crit-rate, or you could add Internal Release is you want something off the GCD. And, of course, Bloodbath and Mercy Stroke are just nice to have around from MRD. I have yet to get all of the DoW cross-class abilities yet, and I can see how certain DoM abilities would be great (Stoneskin, Cure, and Virus come to mind), but it's not a bad way to play.