The cars dynamics are at least 1 or 2 steps above the GTI - see the other post ending 'can't be long now' if you want to read further details. Not sure if it will fully fill any void left if you decide not to pursue the M2 but if you liked driving the std GTI, then what's not to like about a GTI with an R engine in a sharper chassis with a great interior and some might say an improved exterior.
Enjoy it drisser
The dynamics are clearly above the R as well that for the top sports variant (until the CS was introduced) was leaving a lot to be desired. I never test-drove the GTI as it it didn't seem neither powerful nor focused enough for my like but I did try the R twice and although not a bad car at all, there was a distinct level of overall involvement and feedback missing from it that it always felt more like a capable GT than well, an "R" as in "race-car". Funnily I think there is much more "R-ness" in the Clubsport in terms of driving feel, setup, interior and exterior than there is in the R. Anyone looking for or prioritizing the same things, there is probably no dilemma between the two cars. Which is good as being quite different after all they can meet much broader requirements.
How do you think an R should differ from a GTI?
I think VW have always tried to make the R(inc 32) a mature fast car like the RS Audis.
While the GTI can be a more 'fun' (hence the '40 years of fun' slogan that's been bandied around this year).
Having owned an R and now a CSS, I find the R a bit one dimensional and 'normal' unless driven hard, something that's hard to do on the public road while the CSS seems to require a lot more mental processing to get the best out of it, managing the amount of throttle when taking into account the grip available, tyre temperature, ambient temperature, road surface, steering lock applied which makes it more involving.
For example I've seen more ESP activation in my CSS in 200 miles than I ever saw in my R in 8000 miles and I don't think CS Ed40 is all that different.