Having owned both (R27 and now a 200) I agree with the 'evolution' comment, not massively different but certainly different enough to know things have been tweaked and updated. Is it going to be significantly quicker on a track, doubt you'll notice anything tbh however where it does show its 'evolution' is in everyday driving - both doing the boring town and work runs as well as on spirited drives. The quicker steering whilst not obviously different does actually come into play when you are on those flowing A and B roads, again it's not going to get you around the corner any quicker but it just gives you that little bit more flow and satisfaction (no lies here, it simply contributes to a more flowing drive, can't think of how better to explain it sorry), makes the driving experience a tad better imho. Same goes for the engine and the tweaked low down torque and different gearing, the torque certainly helps on the day to day driving and makes for an easier drive but on a lap of a track it wouldn't come into play. The chassis tweaks are also noticeable, whilst the 200 with Cup chassis (only had Cup versions as the R27 did too, obviously) is firmer the damping is also more controlled, less crash and wallop over the rough stuff - perhaps the most gains here for track work (although not gonna break any track records) as it maybe rolls a tad less and does allow a novice to get more from the car (perhaps?).
I think most of the enhancements and tweaks are mainly around the inputs that the driver gets rather than raw pace, it just feels a tad more complete - but I don't mean that the 197 is bad in any way, I really liked the R27 but it's simply a natural evlolution over time where a little more R&D has gone into certain areas.