I tried the HGDB method for the first time and the first batch was terrible. Second batch looks must better, but when tried as espresso it came out in 6 seconds (2oz). I was using 17.5 grams and my normal setting for fresh beans. What the heck!

Well... not nearly enough info to go by... but being the master of botched roasts myself, the question I'd ask in the absence of photos or roast details would be: do you get much bloom if the grounds are immersed in water?

I just did a cupping and there wasn't much crust or bloom.
I Chemex'd a smaller (30g) batch I did and it did bloom some, not a crazy amount. I roasted them to what I'm guessing is City.

I've had unspectacular blooms with under-roasted coffee... any chance of that being the case? Have you cracked open a bean to check uniformity?
Any further details on your roast?
I'm really not the person to be answering questions like this... but it looks like no-one else is biting... I'd imagine with less bloom there's less resistance to water movement through the grounds.

I roasted my very first batch in a popper and came to 1st Crack at 2 minutes of less, I had that stuff cupped at the local roaster and the q-grader there said it was a bit bready smelling and thin...too fruity all the way through. I'm pretty sure I went too light on the roast.

This batch I heat gunned it and got the 1st in about 10 minutes, but the beans are funny looking and a lot of the chaff is still on the beans, maybe not enough stirring. The drip tastes better than the last batch but as espresso it's a no-go.

96 oz DB
1,000+ Watt HG
10 oz Green Beans
Bring to 1st c. in 6 to 6.5 minutes, ease off heat when crack is underway.
FC in near 10 minutes; FC+ in 10.5 (9+ will work, but this gets into judging flavor profile)

All the rest is technique and familiarity--subtleties of how fast you ramp up temp, when to back off, and judging degree of roast for particular beans. But until you are convinced otherwise, stick with the times above. If using a mid-size bowl (64 oz) cut the batch to about 8 oz.

Before I read that reply I decided to do another batch, this time I got a steel bowl for $1 to created a path for the beans. I used between 1/3 and 2/3 cup, closer to 2/3. Didn't weigh. For some reason it took forever to get to first crack, about 13 minutes? Maybe I should hold the heat gun closer. I started on lower wattage until 5 minutes, maybe that's a no-no. I just took a pic, they look weird under the light, look much brighter than normal.
http://farm6.static.flickr.com/5096/5472415258_b26d31389e_b.jpg

Ugly looking roast. Sounds like baked beans and an uneven roast.

I've never tried the HG/DB but had a thought for new Roasters of putting a thermometer in the bottom of the DB, no beans, and shot the heat gun at it at different heights and settings to get a handle on what degrees your applying. Then experienced HG/DBers could more easily steer a new roaster with heat control and temps. and agitation.