Interesting enough, this is exactly what we've done except we did not sell the R44. It is now our second machine for light job and tight confined landing pads in the jungle.
Cost, well if your cie can afford it, sure upgrade...but all costs will double as ours did like Fuel, insurance and maintenance. At the end of the day, the R44 was as good as what the EC120 does now. How just remember which way the pedals go.....
Cheers
WLM