I've opened a few of these locks, most of the time there's good loot inside and not like in oblivion where you'd only find 5 gold or something. Recently, I did encounter an expert level lock.. Which gave me 17 gold for opening it. Great, seems the random loot from oblivion is still in and super-hard locks aren't worth your time (and lockpicks).

What's your experience of these dungeon chests with high level locks on them?

i think loot from some chests are completely random so u just had bad luck
still the xp from unlocking the lock is nice by itself i guess