for me anyway I found the dual flanges to seal inconsistently for my ears anyway, some days it works some days it doesn't (maybe I'm just weird like that)
but I much prefer the single flanges that it comes with (try both the medium and the larges, and even the smalls, if it works for you). the silicone used it not bad! (not as well sealing as the sony hybrids, but I found it to be the best based on whats given!).
in regards to the comparison to the gr07be, i had made a comparison video a while back on it, i think you might have seen it already
but long story short
gr07be- less bass, but tighter and faster, better layering as well, midrange is leaner and clear, treble is more refined and better extended.
vsd3s- fuller bass, a bit slow for electronic music, but impact is good! midrange much thicker and chunkier, treble i think is a bit more sibilant > gr07
still love both of em, i used the vsd3s when i need a bit more isolation--> tube commuting
gr07be for basically every where else.
but of course i use other earphones as well! =P too much gear, not enough ears to go around!