I really doubt the BMW is running at 3000psi. We use the same hardware, and Bosch has a safety valve at 2500psi...
Both designs are capable of good fuel mixture. Just have to have a good model, and figure out what you really want. Both rely heavily on the piston design for some special tuning one a cold start, too.
We run closed loop all the time, too- again, we use the same Bosch parts BMW does. I can't tell you how rich we run (although I do know it... ) but it is richer than 13.5:1. Again, I doubt that BMW is really running that all the time, as you actually get more power out of 12.5:1. A lot of the fuel you put in is very related to how much spark you can run, and more important, how hot the exhaust is. Outside of WOT first and part of second gear, most of the enrichment beyond that is to keep the exhaust temps from damaging the hardware- and that goes for pretty much any engine, not just turbo DI engines.
Perhaps at the start of an accel, BMW targets 13.5:1, but by the end, more than likely, they are closer to 11:1. Peak power 12.5:1. Turbos run ok down to 11.5:1 w/o much penalty, and it's good to keep components cool (relatively speaking- keep the exhaust under 1700F).
Can't say much about the oil dilution- didn't keep too much track of that part of the testing. I know it's a big concern, and a lot of people were working on it, though.
Eric