The main difference you get with a stiffer TAI is the amount of vibration at the clutches friction point. The problem with a DSG car is that you cant control that friction point at all so adding a stiffer TAI can annoy some people. On a manual car you can up the revs a little bit which tends to reduce the vibration considerably when using a stiffer mount.

Im a big fan of replacing the whole pendulum mount as with the BSH setup. Its more expensive but the re-engineering the entire arm has allowed them to product a product that is not only unoffensive to drive with but actually feels more solid than with just a TAI. Its especially good on manual cars where the standard driveline shunt really is more noticeable through the clutch pedal.