The ideal is to "enhance" the grip, not necessarily replace knurling. The down side to knurling is that it'll tear up whatever you clip your light to - shift pockets/pants pockets.FYI, 4Sevens.com informs that they use a proprietary coating on the Preons to increase the roughness to the touch (at the microscale).
It is true that the Preons are not quite as slippery as I would have expected from their appearance, but the coating is still not as "grippy" as actual knurling. Switching modes one-handed is doable in 1xAAA form, but not as easy as some other lights.
Yes, one-handed operation for the P1 is not ideal. The P2 setup as a "pen light" is not bad.
One other thing - if the colored Preons get a little "slippery," wash it with some soap and water to get rid of the oils that fill the tiny grooves and the original grip is restored