Don't think it matters what you have at the moment. With nearly 2000 twin ATPL etc haven't noticed any difference since when I had a half or even third of this.
Seems to be very little movement at any level at the moment from what I can tell.
Think also night hrs are very important. That's often what I hear, ' oh, if only you had 500 night!
Whatever you have someone will always want more....
The amount of PC12 and caravans getting around, I would say having 500 turbine will become more important than 500 twin.