I took the nuclear option and deleted everything of a personal dispute that was surprisingly carried on in this thread between two regular forum contributors, including some problematic remarks that sparked it.  People really should know better than to do this.  I've sent PMs to both of them. 

It was 8:15 am here in North America when I sat down to my computer and encountered the mess.  That accounts for the several hours delay between these posts and my dealing with them.  Thanks to those who sent me messages that something needed to be done.  That's very helpful to a moderator.

Annnywho.. I think 1...g5 is one of those defenses that can be fun to play, and can even become one of your pet surprise weapons. But if you're looking for a solid lifetime defense, I would recommend you look at something more classical and sound. You mentioned using it only for online blitz though, so I say, go for it. Experiment with it, and your chess understanding may improve from it.

I cautiously warn you, though, that somewhere down the line you may become disenchanted with it (usually after you discover it's weaknesses). Kind of like myself and the Modern Benoni. But still, I learned some important insights from that experience, so I say it's worth it to explore attractive trails, even if they may lead to dead ends.

Cheers

Thread split?

To be honest 1...g5 is not total garbage, but in your given variation with 5...Qa5 6.Qc2, ...g5 seems worse than ...g6 since Black has to spend a tempo on defending the g5-pawn and White can gain the edge on the kingside with a quick h4. Furthermore, even the better version with ...g6 instead is not held in high regard by blitz. 

Another interesting option is the modest 2.d3!? Bg7 3.Nc3 e6 4.g3, when White has a small edge. 4...h5 might work well in blitz, but the simple 5.h3! makes it difficult for Black to generate real play.

These articles may be worth a look:
http://www.chesscafe.com/text/kaiss05.pdf
http://www.chesscafe.com/text/kaiss15.pdf

I'm getting good games with this, and always have, as far as my blitz. Is this just very uncharted, or does it have serious flaws?

Usually, I get either some tactical melee with:

1. c4 g5 2. d4 Bg7 3. Bxg5 c5 ... say something like...4. Nf3 Nc6 5. e3 Qb6

Or, 4. e3 Qb6 5. Qd2 cxd4 6. exd4 Qxd4 (Traded pawn g5 for better d4 pawn, a strategical plus.)

2. A kind of a "Beef-Eater" (Dzindzi-Style) with  1. c4 g5 2. d4 Bg7 3. Nc3 c5 4. d5 Bxc3 5. bxc3 Qa5 6. Qc2 

3. Some kind of eventual c5 from black making a Symmetrical English with g5 added instead of g6. (must have pro/cons)

4. A better, faster King's Indian/ Reversed closed Sicilian (as I have saves a tempo from g6-g5 [got it in one go])

What does Marin say? I have his first book (Grandmaster series) which I read a lot these days, but not the other 2. how about Kosten does he or any other modern source cover 1...g5?

Resistance is Futile. 

Merovingian