>>2603768This, except if you want, you can really leave the ND filters at home too, if you're willing to spend a few more minutes in post. The best IQ you'll get out of long exposures will come from the averaging technique rather than using an ND.
http://www.verdantvista.com/tut9Personally, I just carry a decent polarizer. A CPL is typically 1-3 stops of light cutting itself. Sufficient for most things I use long exposures for (muh running water), and I can always average 5-10 shots if I need longer.
