I bought the Samsung S Pen Holder Kit today. It was 900 baht (about $30) at the Samsung shop.
I have a Note 2, so knew the S Pen worked well.
The holder feels a LOT better than the Microsoft pen. It has a rubberized grip and is slightly sculpted, so it feels very comfortable to hold and write with. Also, the button is almost flush, so you can easily feel where it is, but it isn't as obtrusive as the MS Pen.
Also, it seems a little more accurate as you vary the angle of the pen. It seems as if the sensor is closer to the tip of the pen on the Samsung, and further up the pen on the MS.
As an example, if I try to touch a point on the screen, I can have the Samsung at 90 degrees, or about 45 degrees and the dot lines up with where the tip is touching the screen. With the MS pen, at 90 degrees, the dot line up with where the point is touching, but at 45 degrees, the dot is a few mm toward the eraser end of the pen.
Ill be using this full time and just keep the MS Pen in the SP case as a back up.