I've been on dA for a little while now, and regularly submit my Inkscape-drawn comics to several groups. Despite having joined the Inkscapers group some time ago, I've never submitted to it as it always gave the impression of being a showcase of works that were by invitation only.
If it's to be opened up for anyone to submit to, a clear message (and some rules) on the main page would be a good first step.
I would also increase the number of folders a little further, or broaden their names a little. My first though was where my webcomic would go: it's not a caricature. It's potentially a "Scene", but will that result in it being muddled up with landscapes or still life? "People n Portraits"? Possibly, but that doesn't really fit either.
And how much of a piece has to be Inkscape-created for it to qualify? A little final touching up in The GIMP is probably okay, but where do you draw the line? Is it a showcase of what can be done in Inkscape alone, or what can be done with Inkscape as part of a larger workflow? And if it's the latter, should it be a requirement for artists to mention their other tools, so as not to mislead people as to what Inkscape is capable of?
Opening up this group is a great idea, but it's probably worth taking a look at some other similar groups first to see what they do.