How much faster is the SB-250 than the SG-250 when grinding HSS steel? I'm trying to decide if it is really worth buying the a second grindstone.
What's your purpose? If you want to sharpen planer blades, then I think it is a worthwhile investment. If you're looking to shape turning tools (an infrequent task for most turners), I would be more inclined to suggest the BGM-100 kit and an inexpensive dry grinder. For approximately the same total investment, it will be faster for shaping than the SB-250.