Although I've not flown one myself, the -9 is reportedly nowhere near as "twitchy" as a 6/7/8, it's supposed to be quite stable while still being responsive and have noticeably heavier stick forces than the others. The 4-seat RV-10 also is not twitchy at all, I've flown a -10 and it was very easy and pure bliss for a big 4-seater, waaay much lighter on the controls and responsive than my old Cherokee. I was told it is just a little lighter on the controls than a Bonanza, but I've never flown a Bo, so I don't know how they feel.
Saying a -6 is as easy to fly as a Cherokee is a bit of a stretch. It's "easy" as in the control stick forces are very light and you don't have to push any controls hard, but it is much more "difficult" to fly than a Cherokee in that you have to be very gentle on the controls and be on your toes, quick thinking, and paying attention all the time prepared to make brisk changes in pitch or roll when needed, and to not chase the airspeed needle coming down final. Yeah, you can definitely say a -6 can be considered "twitchy".
I flew a Cherokee for 10 years and 800 hours, and you can basically turn your brain off in the landing flare and the plane will land itself just fine. In the RV-6, you're flying the thing until you shut the engine off. The old saying "You're not done flying, till you're tying..." really applies.
Also a Cherokee has a 30 degree per second roll rate... the RV-6 is about 150 degrees per second roll rate. To stand a Cherokee up on a wingtip in a really steep bank takes both hands on the yoke (or better yet one hand on each yoke so you can get more leverage
) and a mighty heave. The -6 just needs one finger and your thumb on the stick and a slight flick of the wrist and you're at an 80-90 degree bank like *right-this-split-second*
.
Once you've become accustomed to how an RV-6 flies, then yes it is "easy", but as I've mentioned elsewhere in the past... my transitioning from the Cherokee to the two-seater RVs (mostly -4, -6, -8) was a lot like learning how to fly an airplane all over again for the first few hours until I got the hang of the extreme nimbleness and responsiveness after so many years and hours of flying a wallowing pig of a spamcan and having that kind of aircraft handling experience so thoroughly engraved into my brain.