Diversity is always welcome. And be it for the sake of choice. Or simply to avoid a MEGA link that does not work for some. A quick and dirty course depository is not a bad idea, imo.
Richard, about your 5 points...
1. See above
2. Good question. Jimbob59 should answer it - he did not use the pluralis majestatis, that's quite sure.
3. OGT does not require course rankings, but invites them - even saying "please" in one thread. I'm with jimbob59 on this one: I find any form of ranking rather annoying, for private reasons of my own.
4. I suppose you meant desginers, not developers? Yes we do need testing, but whether this is taking place on a platform or in private with a few friends is up to each one of us.
5. Okay, neat freak, we have a rather messed up separation of labour already, with OGT in the mix for course downloads and tourneys and with Steam the Awful Game Pimp in the background for more downloads and asset sharing. Oh, and with the PP social website, which... um... also does something, I don't quite remember what, only went there to get my Speedtree coupons, otherwise... I like my things in one place, too. But that's just not on offer.
So tell us more, OP. I'm happy with the job OGT does for designers, and I appreciate and deeply respect the gents of OGT who are seriously committed to this, doing a marvellous, voluntary and unpaid job for this community (This ought to be mentioned every now and then, and never taken for granted, btw). But let's see what you've got and keep an open mind - don't go all Dogga on us, with hehes and misplaced lols and cryptic fragments that leave us guessing. Build your case and make it.
6. You mention on your site that you do not intend to double-post downloads, indicating the courses will not be spread over several places and be made available either on your site or at OGT, but never on both. Did I get that right?