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So, let's just presume that you get the same number of visitors from each of the above sources. What source is convering better than others?
Something for you to consider: Some of my longest domain names (majority are currently parked) have the highest clickthrough rates (on the ads that appear via domain optimized links on the landers). I'm not talking about the old generic take-all-commers landers.
Self-selection? Self-filtering? "Dang, I just typed the long URL I darn well am going to click on something other than the back button!"?
One thing that I am able to add to the mix, via the system I use to park my domains, is to upload "on domain topic links".
Bottom line: Any doubt that the more filtered the traffic the better the performance of the visitor, measured by favorable behavior? The clearer the signal "this is what you will find when you arrive here" the more likely that those who arrive will click on something that is responsive to that which motivated their journey.
So, my 2cents: Grab some on topic longer URLs, especially if the value of the click is high. Only takes a few clickthroughs to pay the annual registration fee.