You'll always get some mist out of the breather on a draft tube engine. If its a pretty steady but light stream all is well, if one cylinder has a broken ring/s you will see a choofing effect from the breather and the ammount will be pretty large.
The draft tube can get blocked but this is easy to test. If at idle and blowby is at an acceptable level and the engine is just expelling hot light gasses you will get, as i said, some light mist from the breather and not much if any from the draft tube, as the engine makes more blow by gasses you start to get more mist from the breather and some from the draft tube also. The gases are hot and will naturally rise to the breather, if there is too much gas it will come from the draft tube too.
Now, to check if the draft tube is blocked, real easy, drive till you normally would see gasses from the breather at idle, now just block the breather and see if the gasses now come out of the draft tube, if yes then all is well, if no then the draft tube is blocked. It is easy to remove and clean. You can also clean out the draft tube fitting cavity in the block but be carefull not to let the sludge and crust go further into the engine.