I have a video on here about me using my CPBF. It's a pain in the ass, but the more you use it you get a hang of it. Never used the Beer Gun, but I question it on highly carbonated beers. Even the CPBF foams up on some of my brews.
This is my video: http://www.aleiens.com/video/counterpressure-bottle-filler
Haven't used either one, but I know some people in the club have had good results with them.
Me, I use a 20" long, 1/4" plastic tube inserted into the dispensing picnic tap of my kegs, with no (major) complaints so far (see disclaimer below).
Unless I'm doing a lot of them, I chill the bottles in the freezer first, decompress the keg, and use minimal pressure to fill the bottles with very little foam. The beer is already carbonated, so if I'm serving it later the same day, it works out well. If I'm saving the bottles for later, I drop a few Munton's Carb Tabs into the bottle and quickly cap it.
Disclaimer: It's not a perfect method, by any stretch, as I've experienced some "flat-ish" bottles, but for the price ($1) it certainly does the job until I can convince the wife to let me buy a beer gun... :)