i confirm, i did the test beetwen live version and beta online,

blue giant kill give 2x less xp to your thrall on beta online
same for gorilla 2x less xp

so seem that the xp curve for thrall in beta is going two time slower (at least) than in age of sorcery.
for thungra that i try to level up more a matter of 2h 2h30, he comes up with 400hp at level 0, so far 1351hp at level 15.