First thing, the extra drag on the cylinder and crane mentioned earlier disappeared after about 24 hours. I suspect this is because the oil is more viscous than my usual lubricant and did not migrate as fast.
I finally got to the range Sunday (9/11/2011) and put about 300 or so rounds through the 686. The ammunition that day was a mixture of commercial 38 +P (158 gr Speer Lawman) and several different .357 handloads.
The handloads were mild for a 357 -- mid-range loads of Power Pistol or Unique. La Esposa came with me Sunday so I didn't bring any of the hot magnums. I have this recurring nightmare of her inadvertently picking up a full bore load of 2400 powder back of a 158 gr XTP flat point and refusing to ever shoot the gun again. Hell! Since my carpal tunnel relief those bastards smack me hard enough to cause some numbness in my fingers after less than 50 rounds.
The gun performed flawlessly -- as usual. After I came home I gave it a thorough inspection, especially looking for the crud that builds up in the nooks and crannies of the S&W lockworks. I can honestly say that the gun did appear cleaner than I expected. This may be because of the powders or ammunition used that day but I am, tentatively, calling it a win for Slipstream. FWIW, I was sufficiently impressed that I stripped, cleaned and lubed my 625 with Slipstream.