From someone who is Chieftain endorsed and currently flies a single turbine I can say that the right single turbine is streets ahead of the old piston twins in so many ways. There is a reason why there are more new turbines appearing on the scene.
My machine burns barely 200lph on average, climbs like a homesick angel, carries more than a comparable twin, has nice toys for the pilot to play with (very important!) and EVERYTHING works
That is only the start of it. They are smoother, quieter, and once you have flown one you will wonder why people bother with 30 year old piston twins anymore. There has to be a strong case for new technology and its associated safety and maintenance benefits. I think a lot of people in industry are starting to feel that just because a machine has two donks it doesn't necessarily make it safer compared with some of the current alternatives...
There is plenty more that can be said I'm sure!