I use corn cob or crushed walnut with Midway case cleaner added. Never had a problem with them coming out nice and shiney. Never heard of the iosso case cleaning kit! Then again there is probably a lot I never heard of!
I had some of these in the shop several years ago and tried one for myself. Using a tumbler and media was much easier and less messy. Perhaps their formula has changed for the better; however, I will stick with the tried and true.