Al, I was not too different to you went I went for my 407 rating (in terms of hours)...
I did my 206 rating before my 407, with about 25hrs on 206, and R44->206 was straight forward from a flight handling characteristics, you just had to learn about operating, starting and limitations of the turbine...
206->407 was straightforward from a turbine perspective, as 407 has push button start and more power, though the flight handling characteristics were very different.
You could get away with large control movements in a 206 and 44, though with the (smaller?) 4 blade rotor of the 407 you needed to make much more precise, smaller inputs... it can dance around a nickel in the hands of a skilled pilot.
That being said, the R44-407 should be an memorable conversion...
I would be interested to hear from more experienced pilots out here with 206 and 407 time, if you would think it better to get some time on a 206 before doing 407, or not, and why?