FTR - and I have an upcoming blog post about this - I think any of the consumer themes can be pushed PRETTY far. It just takes some McGyver-level problem solving to do considering the backend and no ability to upload folders or FTP access.
What I'd really love is an active hub in which to discuss SS hacks and mods - SS closed a suggestion I had as a solution to a problem people were having with galleries, and I think that's a shame.
Truthfully I find the one-by-one file upload an epic PITA. What I do instead is use my cheap hosting I put my Wordpress sites on and link my scripts, etc. from there. But if you're locked into needing https secure access, that won't work. I don't ahve a shop on my page so i'm fine without it.
In my experience with just a consumer account - there's some things you can't really change much - like lightboxes and galleries. You can CSS 'em to do some things they don't do normally, but without access to the backend code that launches the lightbox there's not much you can do.
(SS closed this, but I think it's useful)
A solution to something like that is to buy a cheap gallery/lightbox plugin that uses JQuery and do your galleries manually. Not TOO much of a pain if you've got Photoshop and can batch automate files to name themselves 1.jpg, 2.jpg, etc. - depends on what kind of effect you need.
Same with sliders in headers - SS sliders are strange to me. But there's jQuery ones you can implement and once you hide the default header it'll take its place if you write your code correctly.
Truthfully (and this is going in the blog) - I think people who say SS is for designers who don't care to touch code, just make pretty blogs, are COMPLETELY off base. I have to do a lot more creative problem solving on SS than I do on say WP or HTML5 sites.