LLLL.coms are all registered.. L-L-L-L.coms are not even all registered..why choose L-L-L-L.net instead? if u really want get some L-L-L.com in the aftermarket or register L-L-L-L.com instead of .net if u insist but not a good idea.
I think l-l-l.coms make sense, but I don't know why anyone would go for an l-l-l-l.net unless of course it's a REALLY good 4-letter word...like p-o-r-n or something that popular.