You're welcome!
It seems like ABS Bosch 8.2i of the first production years is the main culprit of bad brake pedal feeling.
I once test drove a friend's Polo 6R GTI MY2010 with 288mm front brakes and Ø22,22mm MC combined with ABS Bosch 8.2i: the brake pedal was very spongy, with poor reactivity and long travel.
Then, I test drove another friend's Polo 6R GTI MY2012 with same 288mm front brakes and Ø22,22mm MC/ABS Bosch 8.2i: the brake pedal feeling was very good.
A week later another friend of mine bought a Polo 6R GTI MY2013 with 310mm front brakes and Ø23,81mm MC combined with ABS unit Bosch 9.0i: the brake pedal was rock solid and extremely reactive.
Then, my mum bought an Audi A1 produced in late 2011, which has 256mm front brakes and Ø22,22mm MC/ABS Bosch 8.2i: the brake pedal feel is extremely stiffer and more reactive than any older Polo with the same brake setup I test drove.
So, I arrived to these conclusions:
- the ABS Bosch 8.2i unit of the first years (MY2009, MY2010 and maybe MY2011) has an internal circuit which gives a bad brake pedal feeling (spongy, not reactive and with long travel), especially with 288/312mm front brakes.
- starting from MY2011 or MY2012 (I still need to discover it), ABS Bosch 8.2i unit has been updated and the brake pedal feeling got much better (infact my mum's A1 still has an 8.2i unit, but it has a newer hardware and software revisions than my Polo's MY2010 ABS 8.2i unit).
- starting from MY2013 ABS Bosch 9.0i unit has been introduced, maybe to completely fix this problem and to implement new functions.
So, in the end, I think the solutions are 2: upgrade your MC (like I did) or upgrade your ABS unit to a later 8.2i revision or to the newer 9.0i unit.