It does work.
I told Garth about it a short time ago, so he could test on similar success.
I prefer low temperature glue, as opposed to high, because it gets solid faster. You place it on the pvc, and the foam, and then quickly apply them together. The foam melts just enough to bond, and the pvc stays firm.
The low temperature creates this sort of tack, in which the glue is still sticky, but not molten and liquidy.
Then just tape it to hold, and viola! Done.
Almost all my weapons are made that way. Cheap, and seemingly more effective than DAP.