Nice, ty for the guide.
I've made some random sync down toons and it's been fun. FYI- Flexweave underlay does work (presumably you can enchant an heirloom and send it to your twink if you really want that.) Spinal heal injector (ENG belt tinker) works as well, w/ similar heal stats. Belt frag, glider tinkers don't work. Bomb consumables don't seem to work, nor Alch trinkets... I'll eventually check if nitro boots (belt tinker) works.... while most elixirs, flasks, food DO seem to work as per this guide.
I'm sure you guys have posted this, but just to confirm, when syncing down, Blizzard puts you on a template - as long as your gear is ilvl34+ and no empty gear slots - your main stat is 199, and all secondaries are at 55 (all in teh 11-13% range, except mastery)... not great, but not terrible. However, I'd have to double-check if applicable race-specific baseline stats and/or racial bonuses were incorporated/addded to the "templated" stats while zoned inside BGs... but I think they were.
Statswise - lvl20 twink>levler with heirlooms enchanted>Syncdown, but in terms of playability, it can be flipped depending on the class/spec due to extra abilities ofc.
Healers seem to be the best candidates for syncdowns, while DPS look too underpowered. Heavy CC cllasses such as rogues may have lots of potential as well.