I recently cut DTFB with my Basic without melting or flames, but don’t remember the exact settings – I’ll look them up tonight and post them.
Still working on the appropriate score settings to allow easy folding edges à la Flite Test designs, but not quite there yet.
Be advised that most foam boards with the paper-outside foam-inside sandwich are PVC foam = highly toxic fumes like vinyl. None of my signage vendors will cut it on their lasers.
Wish I’d known that before I tested it. 
(Good news is, I’m still here, so good job Glowforge.)
I just checked on dicblick and another site for the MSDS on foam board. I only found polystyrene as the filler. Makes sense, PVC is really hard stuff. Doesn’t mean PVC isn’t used in some cases. Just means you should check the MSDS first.
Of course PS also has its own laserability issues (it just likes to melt), but in the thin layer used here it seems to work.
The guys at Flite Test have been selling laser-cut DTFB for years. Who knew?
Edit: Now that I think about it, while it’s true that they advocate using DTFB for model planes, they don’t explicitly say that’s what they use with their lasers. I’m pretty sure it’s PS, but will have to verify or run a flame test …
The last settings I used on 0.15" DTFB were 350 speed, 50 pews, and 2 passes to get clean cuts with minimal charing, but be sure to test. 
This needs to be adopted universally. 
Wish I could take credit, but I think it was Tom, Chris, or rpegg that came up with it…
It’s inspired! (Adding it to my vocab henceforth.) 
(Whomever is responsible, please step forward to accept kudos for extreme cleverness!) 
Twas Chris.
Pretty sure somebody else used that before me, I just decided to try to spread it.
Reminds me of the rumor mill in high school…chuckle.
Well whoever coined it…great job!
The important thing is that all the cool kids are saying it, and you want to be cool, don’t you?
Doesn’t everyone? 
Not me. I was uncool before it was cool.
try 350 speed and 40 pews and 2 passes still charred slightly
How about the settings for scoring the foam board? Faster speed with less power? I am new and don’t want to set too many fires, lol.
I use 350/40/2 passes for cutting and it works greats, thank you!
I use 350/19/2 for heavy scores (this gets everything but the bottom paper) and 350/10/1 for light scores that go through the top paper only.
I’m making an educated guess that 350/3/1 give or take would be right for just marking the paper.