I have no experience with the filter you suggest, but the difference between a polarized filter and the in camera ND filters are big when it comes to color quality on sunny days. Also the polarized filter will reduce sun glare from reflective objects , the ND filter will not. You are comparing two different types of filters.
ND filters cut down the intensity of light, polarizers reduce glare, like off glasses, windows etc... carry a polarizer with you... and i even have an extra ND filter with me to be safe! i had a quantaray polarizer when i had my old sony vx2000 , but i only have a clear uv filter for my 100b... the quantaray is great if you want it, but it doesnt last long. for long lasting ones, look for tiffen polarizers...