Just an FYI, it doesn't seem like you can sell merc gear back to vendors. I'm not sure if this is intentional or an oversight on the devs part. Given how much better the Dropped Extravagant gear is then the Group Elegant gear, I'm regretting spending the 1600 Sathir Trade gems on a full set. Much rather have just kept my COTF merc gear while waiting for the Extravagant drops.
I wouldn't suggest it. I exchanged my cotf gear for the new gear (converted to Flawed) and my caster DPS went from about 29k DPS to 8k DPS. I'd much prefer my pre-nerf gear back.
There's no reason not to Convert the gear. Without converting it is worth 0ac, 0hp, 0 mana, etc... Mercs are healing just fine either way
Definitely convert your old Merc gear if you have it. I would NOT recommend buying the new gear from the group vendor in Lcea with your Sathir Trade gems and just wait for the droppable Extravagant Merc gear..