I think it comes down to an "in extremis" thing - only using them when you absolutely have to or if someone else has offered their aircraft and A.N.Other CII operator won't match the low low price. Given the number of light jets on the market place at the minute I don't really buy the "There was nothing else available" thing.
At the end of the day there will always be a brokerage that is offered a CII for £x ammount, a CJ2 for £x+100 and doesn't have the common sense to ask for a match - or even bite the slight increase for a better service both to the end user and to the brokerage.