I took feedback from the comments on my blog and results on the Sonic Fan Games HQ forums. In a typical scientific poll, you wouldn't combine the results the way I have, and you would ask people randomly. However because of the small audience my engine faces at the moment, I think it's fair to say it wouldn't skew the poll results too terribly much. At the most, you would likely find the Linux and Mac results to be slightly skewed.
Out of 24 people, just 4% suggested ProSonic be ported to Linux / UNIX platforms, while 8% said they would like to see it ported to Mac. Between the Sega Dreamcast and the Nintendo DS, it was a very close race. 38% of respondants said they would like to see a Dreamcast port, while 42% said they would like to see it on the Nintendo DS. When the option of "Other" was picked, all 8% said they would like to see it on Sony's PSP. Under normal conditions, the margin of error would be about +/-20%, but because this wasn't done scientifically, the margin of error may be wider than that.
I'm considering doing more polls like this one. I was quite satisfied with the number of people who got involved.