Well its a massive improvement over the tiny standard one.(as is anything you replace for an aftermarket one on a seat, excluding cupra). It holds the boost for alot longer and you still have power all the way around till about 4k and then it starts to tail off, but when the car is remapped it should hold power till 4.5-5k. I havent done any logs as yet because i havent got vag com but people who have have said that the intake temps(think thats right) dont go above 35 even when giving it some compared to what the tiny smic temps which are pretty high.
All in all i think that it is well worth the money, yes its expensive but if your going down the route of remapps ect then its a must imho.
Hope this helps, failing that have a look in the FMIC section at the top of the mk4 thread.