I have one of those clutches in my car coupled with a Exedy 6Kg Light weight flywheel.
You can definitely feel the increase in pedal effort. But you get used to it pretty quick.
It definitely has a much stronger bite than a OEM 6 speed clutch. And with the 6 stiffer springs in the center the clutch itself runs silently but may increase gear noise a little on decel.
If you want you can come around and have a drive of my car to see if you like the feel.
And if you like it I have one of those clutch kits for sale for $700 ONO
http://i71.photobucket.com/albums/i1.../HDClutch1.jpg
http://i71.photobucket.com/albums/i1.../HDClutch2.jpg