The 4 character limit is some MySQL limit, not specifically an e107 - sure there are other threads on this and I can't remember the detail. A Google search with site limited to e107 would work, of course. And I don't believe any of the devs "hate" SEO/SEF specifically.
If I had 3049883+ pages I think I'd find the URLs equally bad whatever system was used - if I'm looking at URLs as a human the most I tend to look at is domain name to see if it might be a likely 'good' site. I've read arguments for and against SEF URLs - not sure any has proved beyond doubt the best approach.
301's I can imagine is an issue - though I've never seen it as one in my sites. But basically only index.php returns a 301 so site rank may be an issue rather than page rank (if there is such a think) as other pages won't return 301 to a spider.
Like I said, my sites have never suffered so not sure what "can" be done. You could start with FURL plugin - but I've heard bad things about that.
So much cool stuff hidden from the masses 301 solution - Administration -> Front page -> Edit and choose Welcome message. Create custom (e.g. index) layout in your theme, and use it for your index.php only. Create menus/plugins and add to your front page everything you need.
SEF is coming soon, top priority areas are Custom pages and News (both will become plugins at some point). Not sure if we'll have time to do it for the initial 0.8 release, but it'll be definitely part of some 0.8.* release.
I've got a beta release at my site of a custom page plugin which gives seo type urls, canonical link option meta description/keywords/page title for each page, copy a page, past copies of pages so you can revert to an earlier version, auto thumbnail images etc. templated, uses templates and can import pages from core custom pages.
First thing I look for in any CMS / Portal is if they are TRUE SEF. I don't give a damn what the search engines say about it. It is my own taste, a style, like how I dress.
I don't care about the extensions (.html) and the numbers I saw in previous posts are not truly 100% SEF. Even Joomla isn't 100% SEF. Well, it is to the search engines but not to the human eye and this isn't good enough for me. The only TRUE SEF I've seen is with MODx. The downfall about MODx is this new cloud thing they are doing using 3rd party websites for themes/templates and other things.
A 100% true SEF URL: domain.com/search-engine-optimization/search-engine-friendly
of course this would be the category and the title of the page
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