ive driven both quite a bit and if you can only afforda 197 you would be dissapointed especially if you can get a cup or a R27, but if you drive a 200 you will find it hard to settle for a 197, jumping from one to the other you wont massively notice a difference but drive both for an hour or so and you will see the difference.
the extra low down torque, shorter 1st, 2nd and 3rd gear, sharper turn in, makes all the difference.
197 and 200s really really need revved much more so than a 172 or 182 so a lot of people test drive them and think hmmm these are no where near as quick as the older ones, as they dont want to be doing 7600rpm gear changes on a test drive but when you own one you will find they are easily just as quick as a 172 in a straight line when on the boil (and i had some quick 172's!!) and cross country they are massively quicker due to the brakes and stability, ive genuinely never felt anything that grips like it mid corner!
however i wont turn this into a 197 vs 200 vs everything else thread!