That all just seems real, errrr......too fast, for me anyway.
I use single flute Belin, but I would probably be more inclined to use 3/8" over 1/2" for 1" material.
My Colombo spindle's sweet spot is 12,000 RPM but I can go any, but I'd be going 7,500 rpm @ 2.85" IPS for 1/2", or 10,000 RPM's...