I prefer the Safariland speedloaders but there are some configurations of J frames and factory grips that will not work well with them unless you want to gouge the hell out of the left grip panel. I found that the extended "handle" of the HKS speedloaders works better for these tiny S&Ws. Also, all of my HKS speedloaders hold the cartridges a little "looser" than the Safariland loaders which hold the cartridges more rigidly. That bit of wiggle aids in inserting the cartridges into the cylinder given the small amount of space between the edge of the grip and the back of the cylinder.
I don't like a lot of the custom or aftermarket large grips with speedloader cutouts that are made for J frames. I know that would alleviate a problem using the Safarilands, but I try to keep the small profile issue grips on my j frames for maximum concealment. It takes more practice to shoot them well with the standard grips but they conceal much better than with oversize custom grips. I find this to be true for me even with quality grips like the Spegels, which I consider the absolute best of the lot.