Hi Dan,
Sounds like you are going through what I went through when I changed the runflats. I've pasted my views from a couple of other threads below:
Ok so I replaced the 205/40R18 funflats with 215/35R18 Falken FK452.
So straightaway the ride was noticably softer. My spine no longer shattered when going over matchsticks or pebbles.
They are much quieter and the ride is a lot, lot softer. Dry grip under normal driving seems comparable. Not driven through the wet yet so will update later.
Edit 1-- So now done 200 miles and am starting to push them round roundabouts. I tend to agree with the review :
falken fk452 longterm test - tyre reviews, the online tyre guide
They do seem to have a double entry to corners when going in hot. You go in and the car has a single slight wobble before it settles in. Not a lot, but noticable after the runflats. But it can be adapted to.
The best or worst - depending one your point of view is the progressive grip. You can easily induce lift off oversteer - which is something I enjoyed in the MX5 but not so sure about in the mini (yet)
So my feedback is they are great as a daily tyre to replace the runflats (£86 fitted rather than £190 for the runflats) but be prepared for some sliding if pushing it.
Edit 2 -
Ok so just got back from the trip to the Nurburgring....
The Falken 452 's were faultless. Really enjoyed going round the ring on them. Yes there are tyres that grip better - but for £86 fitted per corner they were awesome (and much, much better than the runflats). And I've totally got used to the change in how the car feels
Edit 3
I had a long chat with the Falken techies about tyre pressures - they recommended starting with the same pressures as the runflats - and then tuning to taste.