Hi Vaun
Have a Mini 2 door hatch myself. Do not know of anyone with a PHEV Countryman but there’s s thread over on the Off Topic section called “Mini Matters” in which the ordinary Countryman is discussed, particularly its ride. Hope this may help.
Basically, the most important thing when choosing a Mini of any type is drive the thing. Difficult now, of course, but essential if ride-quality is important. Moreover, drive exactly the one you fancy. I drove a four-door hatch as a test. Liked it. Ordered a three-door, expecting same ride but it’s more choppy and harder. Wheel base length seems to make a difference. Go for smallest diameter wheel, higher profile tyres really do make a difference. The adjustable suspension makes a small difference but only two settings: hard and very hard.