Hey holgal, welcome to the forum!
We talked briefly on Twitter, so you already mostly know my opinion. But, to put it out there in public (and to render it more complete now that I'm just speaking for myself rather than "the society" as a whole):
I think your designs have great potential, and I'd really like to see them at least partially integrated into our stuff. The easiest way that comes to mind is merchandise - our Cafepress store is already relatively well-established, and it would take relatively little work to convert some of your work into t-shirts, or launch some neat poster designs for people to enjoy.
A membership pack is also an option that's been discussed for a long time (which is about the only thing Screamer said that wasn't completely incorrect), but with the amount of interest we attract and the limited resources we have, we'd have to find a way to make it as close to self-sustaining as possible. Cafepress merch works great because we only need to tweak it occasionally, but otherwise it just runs itself. The way Daniel's society used to* do merch and membership packs was very high-maintenance - he'd get a local print shop to produce the merchandise, then he'd pick it up and pack/send it off by himself. Right now, I don't believe anyone would be able to spare the time to meet demand, so we'd have to find a way to do it automatically (which would likely force strict constraints upon what we can and can't produce)
The elephant in the room, however, is that you're suggesting a full rebrand of the society. Pushing aside the change-averse part of my personality for a moment, I think we'd need to see more mockups before we could meaningfully talk about a rebrand. The posters/brochures/etc. are impressive, and they give a good idea of the general style you're going for, but they're all focused around print. Do you have any ideas for how to reshape our online presence, or would this be something to look into? Unlike Blanko, I wouldn't say we need a fully-fledged guidelines document just yet, but it is important to note that currently most of our activity is online, not printed.
* - their store has been "coming soon" for a few years now, approximately as long as Daniel's absence