Yes you can HQ it, and has materia.

However, there is a large failure rate obtaining HQ on 50 gear. I've walked around speaking to several high-end PLD's and Warriors asking them about the 11 materia slots and the HQ failure rate. Not a SINGLE one was willing to grind the tokens required for the coke, with a chance of HQ failure, for 11 materia slots for the armor alone and the HQ itself if all were successful.

Also, getting the Materia you want for the piece you want just isn't worth it either. It's so hard, grindy, and random to work getting your set completely materia'd the way you want. Not to mention the minor bonuses you seem to achieve.

No one wants to work on darksteel if darklight is just so much easier to get.

Oh, might i also mention that no one wants HQ armor pre-50? I've got 9 sets all varrying throughout the levels of HQ armor that hasn't sold in 3 days.

WHY DID I WASTE SO MUCH TIME AND EFFORT ON ARMORSMITHING IF IT IS WORTHLESS?!?!?!?!?!?!?!??!?!