I can imagine the R66 as just a bigger R44 with a turbine engine.
True, but wayyy better in any sense. Do a OGE hover on a R44 and you will be looking to find where the wind is coming from every 5 minutes, watching the manifold pressure constantly, fighting the controls and being shaken around, on a R66 you just don't care where the wind is coming from you would just sit there steady. I say that because I fly both almost every day.