Jason, my Silverslaps E and A were at least very difficult under the bow for a week or so, then I started using a tighter bow, generous (but not crazy) Pops, and a slower, heavier bowing technique. While I wipe them regularly, I think the rosin accumulation within the SilverSlaps windings have helped a lot.
This was about 5 to 6 months ago, at this time the SilverSlaps bow nearly as well as the SBW Deluxe D and G... Which, btw, are excellent under the bow, that spiral cut makes a huge difference over regular wackers. Aside from liking how they sound and feel, one other nice thing about keeping the Deluxe D and G on is that it gave me some excellent arco strings to use and compare with while breaking in the SilverSlaps.
I got my SilverSlaps E and A from Mark Gollihur (excellent service [NFI]) and his website is pretty clear about SilverSlaps and Golden Slaps under the bow, so I knew what I was up against and to be fair, was somewhat determined to make them work as well as possible. These wouldn't be my first choice exclusively for arco, but I am not afraid of using them with a bow in front of people now.
(I use an inexpensive brazilwood French bow with white hair.)