So… Is there a way to upgrade Veteran gear to Champion gear and so on? If there is not… does that mean, if I get a BiS piece at the Veteran level (let’s say in M+), I will have to farm continuously to get the same piece on the Champion level and so on? Is that right?
Thank you to anyone explaining as I am still trying to figure it out. I already made a bad call getting rid of 2/4 pieces of my Season 1 tier set 
Just trying to be cautious before I make another mistake that handicaps me 
Yea some pieces can only upgrade so far , then you gota re farm the same piece all over again and upgrade again … who ever came up with this system is a genius
Champion track items cannot be upgraded to hero track. HOWEVER.
The difference between champion track and hero track is 4 ilvls.
If you are looting hero track items, you can upgrade 3-5 hero track items to 441 per week, regardless of what slot they’re on. In the previous system it took three weeks to upgrade a single weapon.
You’re going to have a full set of 16 437 items within the next month, minimum. And as soon as you start doing 17+ keys you can bump all of those up to 441. Not to mention crafted items going to max vault ilvl of 447.
The only negative of this system is you might have to wait to loot the same item again to get those extra 4 ilvl. Besides that you’re gearing faster, have deterministic max ilvl bis, and can multi role easier because you can upgrade multiple different statted items of the same slot for no extra crest cost.
No, you can not upgrade the “tier” of gear. Just upgrading it to X/8 within that tier.
The tooltip on the crest items is a little misleading. It could be read as if you can use the crest to upgrade a max level X into a low level Y. But that’s not the case.
The only real reason for the hero items is to get that sweet mythic tier xmog. I guess you also have to spend fewer crests upgrading them.