It's a highly profitable market maker more than a long term investment fund.

I'd really like to see deets. I've looked, somewhat, and what I've found (including Jim Simon's very few talks) have been ... pretty uninformative.

You're not going to see details. No one who works there (or at similar firms) has any incentive to give away that information. If you come across people who work at one of these firms, you'll find they are extremely cautious about saying much of anything about their work.

The comments you see on forums like this one are just best guesses - educated guesses, but generally underinformed and relatively out of date. I personally consider it a fluke that RenTec is as famous as it is - other comparable firms like TGS have far less notoriety (and are probably better off for it).