I'm not a test pilot or anything, but I have a decent amount of time in 206s and R44s. I only flew an R66 once, two on board full fuel. It immediately occurred to me that it felt very very light, as if the disc was barely loaded, and I made a comment to the owner (who was the passenger) about it.
It reminded me of a lightly loaded R44 with one on board, quarter tanks. And I had gotten into a low G event, with the whole 90 degree right roll and everything, a few years prior in one of those. I had flown it into a mountain wake in Tasmania after dropping some hikers off in the hills.
The difference is of course that the R66 has another 15 or 20kts on such an R44, which makes it scarier to me. A Jet Ranger, at least going by feel, is nothing like it at all.
Just my 2 cents.