Some if not most bits from China are made with cheaper materials and have lower quality cutting edges. That's part of the reason they are cheaper. (cheap labour and no environmental controls is the rest of the reason)
you also wont get tech/ sales support from overseas manufacturer.
Try :: FS Tool :: they have sales and distributers throughout Canada and USA and their products are made in North America.
if you do any nesting they have an award winning dust free nesting system called the Aerotech.