Based on figures on other cars, the difference should be pretty impressive. Most of the cars with a similar level of tune and REVO code do 360hp+
Pump is a very worth while addition, mine gained around 35-40hp across the mid-range when the pump was installed. Bear in mind though you need the correct map to take advantage of the pump.
Its not slipping under daily driving conditions, but generally its struggling like mad to reign in more than 360ftlbs of torque right across the midrange. The other factor is not keeping the clutch in contact with the flywheel, at high RPM's it can occasionally spin up or jump up revs suddenly when flooring it hard.
Not uncommon for the OEM clutch to fail on the Cupra, same thing happens to Ed30 Golfs too. Just big torque and power it wasn't designed for, hence time for something more suitable.
Stg1 cars would probably not be as susceptible as a Stg2+, but even I've heard of failures on stock cars.