The main sore points with sync are in my opinion:

- Endgame synch just syncs most instances to the expansion cap, meaning you can see gaps of syncs between the MIL and the cap being above a whooping 100 ilvl (notably in raids). Some early endgame dungeons have hard syncs, please use more of those.
- Leveling dungeons are tighter and work fine overall, but the old ones are completely outcrept by powercreep, gear creep, mostly before ShB since earlier content was designed around a different battle system with way lower potencies and stats.
- More secondary but syncing down progressively fills up the substats of every piece of gear depending on how wide the gap is between the gear's ilvl and the instance's ilvl. Past a certain threshold players end up with synced gear that is somewhat similar to a full pentameld on every piece.