I kind of liken it the difference between a BMW 3 series and a Nissan Pulsar or the like, they may look similar on paper in terms of what theycan do but there is a big difference between the two as most people can appreciate.
thing is, you could buy a new R66 and about 25 new BMW 3 series for the price of the 120... And you'd probably still have some change left for a couple of pulsars. Like the 66 or not (and it in my opinion, it is more than just a R44 turbine), EC120 sales are going to take a hit.