I have just acquired a #22, but when I was looking on Mr Razor's site other than the weight the #16 looks identical to me. Where is that 10g hiding and do they shave differently?
#22/66 has the "diamond silo", while the #16 has the flat silo. This is one area they differ.
Many will say that the heavier head will make them shave differently ( don't have a #22/66 so can't comment ).