If my instinct & prediction is right, u are also one of the proud owner of a MK5 GTi too? Mine have been remapped to Stage 2 REVO with K04 turbo kit setup plus some secret recipe tunings. Hehehehe...... managed to whacked the highest top speed previously at 29x km/h which made my balls went up close to my throat once. Hahahahaha.......

U should give your ride a try with the new CSC5 to justify its performance according to your driving style.   

XM2 is fuel saving and comfort tyre, but don't expect excellent handling though

Had experienced both GT3 and XM2, both ran from new till they were >5yrs for replacement.

Personally for the 1st 2 years, I didn't feel much significant difference in driving feel between both in the dry, although XM2 provides slightly better NVH over GT3. The car also felt more planted in the wet with the Michelin throughout its usage.

For long term usage, GT3 as mentioned gets hard faster than the XM2, and looses both vibration absorption, grip and noise suppression sooner at each wear stage compared to XM2.

My XM2 set however aged a lot better, rubber though hard doesn't chip at the edges which was quite apparent on the Goodyear's 'shoulder' blocks (I admit I tend to corner hard s'times).

The biggest drawback however is the really high price for an entry level tire that's frankly quite an old design. E.g. I was quoted over RM200 for an XM2 size 185/60 R14, compared to the next newer and cheaper RM180 Conti CC6.