There are plenty of people that have been using alternative fluids with success. I personally use Idemitsu H+, not because they make the Honda fluid, but because I can get it in a 5qt bottle delivered to me for a fair price.
None of the alternatives match the OEM for composition, but with more and more people using the alternatives, its looking like it doesn't really matter. It's been discussed here and in the white paper sub-forum at length.