It won't explode, and it's already a lot.
Outside China, the IE6 market share is now <5%, so it's no big loss if it doesn't look good on these. It has, however, to work, since Opera's market share is not much different and I'm using it as my primary development platform. (A matter of logic, I'd say.) I'm not testing support for Firefox 1.x and 2.x though, ah ah. (<0.3%)
Anyway, once we start releasing our files, I'll probably stop testing for IE6 myself. People will be able to report bugs and stuff that were introduced in new builds, but I won't change Wedge to make it behave perfectly in IE6.
Yes, SMF does it, but remember that SMF2 was started back in 2005, when IE6 still had a 90% market share. We're six years later and they're still treating IE6 support as sacred or something.
Is jQuery going to be used, or are you guys writing mostly your own?
We included jQuery but mainly for user interest. i.e. we don't actually need it ourselves, but we figured that since it's the de-facto library for developers, many would be happy to see it included by default, avoiding the need to include the library separately (potentially breaking other mods using it in the first place.) Everything is taken care of for them. However, early versions of $ had a reasonable filesize. Now, v1.4.4 is about 24kb after gzipping, which is scandalously big. It pretty much makes it hard for 56k modem users to run a site that uses jQuery. And the newest 1.5.x branch is even worse (I suspect v1.5.3 will finally reach the 30kb limit.)
We're currently using 1.4.4 because we don't need more, but support for the latest versions seems pretty much mandatory to me. Admins have the ability to choose whether to load jQuery locally or from a CDN (I would recommend the CDN, if only because you get the benefit of cross-domain caching.)
I don't really know what to do about the filesize all in all, but I know that I spent a LOT of time optimizing the source code and templates to actually make it faster to load Wedge than SMF. (Even with aforementioned 56k modem.)
I guess I still haven't found my peace with jQuery. It has some nice features, but nothing that we couldn't implement ourselves. Hopefully, v2.0 will be modular... But I suspect that even if they added some kind of modularity to it, it would still be bigger than the entirety of 1.4.x.