Today I am trying to grasp the difference between {net + verb} and {'e' + verb-lu'}

The way I understand it is, for example with "Sov"

net Sov = it is common knowledge that 

'e' Sovlu' = someone (indefinite) knows that

Thus:

qama'pu' DIHoHbe' net Sov = It is common knowledge that we don't kill prisoners

qama'pu' DIHoHbe' 'e' Sovlu' = It is known / someone knows that we don't kill prisoners

Similarly with chaw' : 

qama'pu' DIHoH net chaw'be' = we are not allowed to kill prisoners

qama'pu' DIHoH 'e' chaw'lu'be' = someone does not allow us to kill prisoners

Am I getting it right ?

My first attempt to answer this never arrived.

The "common knowledge" idea was invented by Klingonists' usage; it is not canonical. Back in the early qep'a'mey, it was a running gag to say net Sov, net Sov! in part because Captain Krankor's imperial anthem uses that in a line. There is no semantic difference between net X and 'e' Xlu', except that the latter is supposed to be ungrammatical.

The rules say that, except for the recent exception with 'aq, one uses net when the subject of the second sentence is indefinite, not 'e' X-lu'. Okrand breaks this rule occasionally, and when and why one can break the rule is unknown.

I believe he breaks the rule for the same reason I do sometimes: it's easy to forget to use net. I think he does it in error. Of course, if he ever decided to explain what's going on, he'll invent some reason why all the examples we have of apparent rules-violations are actually special cases, and here's what's REALLY going on, and that'll be that.

-- 
SuStel
http://trimboli.name