Ultimaker II upgrade with Low Friction Spool-Holder

I'm currently upgrading my Ultimaker II with a "Low friction UM2 spoolholder" the YouMagine user IRobertI.

As I print a lot, I use huge and heavy Colorfabb 2.2Kg spools.
So when a spool is fresh and heavy, there is a lot of friction involved that the extruder needs to overcome.
My hope is to reduce this friction a great deal with this simple upgrade.

Notes:   

• Print "608 mount" ith lots of infill, a large nozzle and thick layers. It needs to be strong.
• M8x140 is plenty of length. It should have a hex head, so you only need 2 M8 nuts
• You can use counter nuts (4 in total), so the nuts stay in place even with lots of vibration over a long time period
• Use a bolt that has threads all the way (no smooth shaf and only threads at the tip)
• Clean up the inside of "608 Core2 90mm" and "core 1", so a 608 bearing can be inserted into the far end
• check the order of assembly:

1. insert M8x100 hex headed bolt into "608 mount
2. add M8 nut and 608 (skateboard) bearing, so "core 1" has a small air-gap wi "608 mount"
3. add "core 1"
4. add spacer
5. add another 608 bearing and M8 nut (don't overrighten)
6. add "608 Core2 90mm"
7. add final "608 nut"