Interesting, two different Brewers Choice websites.
I've made a couple now for SWMBO which I got from Brewers Choice
http://gfhomebrewing.com.au/.
The first two were failures, but the third has been a hit. She now likes it better than any commercial product.
I've been playing around with my own recipe, and have found out two key things.
1. You need to add some sort of sweetening ingredient such as honey to help take away some of the sourness.
2. A long lagering (about 4 months) has reduced and rounded out the sourness even further.
This results in a beer that still doesn't tastes like regular beer, but is still very drinkable. When serving, I carbonate it up a bit higher, around 100kPa in the keg, and make sure it's drunk cold. Not necessarily super cold so you can't notice the sweet adjunct flavours, but as it warms up the sourness becomes more prominent and is harder to palette.
I currently have a new brew in the fermenter. This is a completely different recipe to the last.
In addition to the 2.8kg of extract, I have added 0.5kg of organic rice syrup, and 0.45kg of home made candi sugar. Hallertaur hops and fermented with Nottingham.
The other things I have noticed is that GF beers are extremely slow fermenters.
Good luck.