All depends on the quality of the letters. Anything from reg fee all the way to a lot for something like PORN.net
im no expert, but if the 4 letters make a pronouncable word (ie. mink), it will be more brandable, and therefore sell more than one that isnt pronouncable (ie. kpql) good luck
5 letters is better than the 4 letter dot net domain. there is no potential to register thee domains.
we have 4 letter dictionary word .net's (not the greatest words, but still they are pronounceable dictionary words) & nobody is buying them really. .net is really in the same niche as .info/.biz/etc.. these days. .org is far more liquid.
Are you saying having a .org is better than having a .net? If that is true I really didn't know that.
I have some really nice LLLL.net (IMO)... Completed 4 sales while on vacation... Just finished the 4th sale to an end user last week. Not "WOW" amounts, but still good money. Very satisfied with my investments.