I have a 2 seat machine that I use for business on a regular basis, it is only really cost effective when you value your own time in excess of £200 h.r. It would be more usefull if I had a pilot who could just drop me off at a clients location and then go and do all the shut down, refuell, pay landing fees etc and then have it ready rotors running when I arrived back in the taxi, then it might just be cost effective but you would have the expense of a pilot to pay so even then probibly not.
Mind you I have tried to convince the tax man that it is cost effective
and at the end of the day it beats the hell out of driving!