When do you replace gear (DoW/M)?

[Vandril]

When I level new classes from 10-50, I tend to upgrade all of my gear every 10 levels or so. This means I'll sometimes skip a "tier" of gear, as there tends to be one every 5 or so levels. Doing so has never held me back in leveling or dungeon runs. Having HQ gear for level 35 while being level 40, for example, is a lot like having the level 40 NQ gear. Only once 10 full levels pass do I tend to notice a real drawback to using my current gear and feel like I should upgrade.

All that said, I'll generally make an exception for my weapon. I like staying up to date with weapons.

Exceptions to this are tank classes. While leveling tank classes, if I am ever running a low level dungeon, I ensure I am in the best HQ crafted gear I can be for the level. It really helps ensure smooth runs regardless of who you get in your party.

Leveling from 50-60, though, is a different story. Every 2 levels has a new tier of gear. I will tend to follow my old pattern of double-tier replacement and replace gear every 4 levels (every 2 tiers). I'll make the 50 set, hit 54 and use the 54 set, hit 58 and use the 58 set, then grab whatever non-crafted pieces I can to fill out my 60 gear and go from there.

[Risvertasashi]

All that said, I'll generally make an exception for my weapon. I like staying up to date with weapons.

...this is actually really good advice. Just in case the OP isn't aware, weapons have the most heavily weighted stat; it's worth extra effort to keep up to date on.