Option: plus mic preamps, voila, a new recording interface with creme de la creme converters

I think it is very realistic of RME not to create that (ADI2pro+micamp+totalmix). To build mic preamps that are on par with this converter quality is really to expensive. To build a studio that is quiet enough is even more expensive.
The misconception is that this better conversion leads to anything meaningful in all situations, better accuracy. But it does not. It is all about the accuracy you need for a given source. If the source has a noise floor of -80db you don't need 120db capable converters. If your mic has 1% distortion you don't need 0.0001% from your interface. Yes if you record at a scoring stage with an orchestra and a piece with tremendous dynamic range, you will need top notch equipment, but I guess this is not RME's target market. But listening to these recordings with the ADI2 pro/dac is what it is all about.
It is very interesting that we like the non linearity of analogue  and are obsessed with perfect converters. Yes in the beginning of digital it was a little harsh because of the used Nyquist filters, but from I believe the third generation of cd converters that was much better.
I understand (and have myself) of course the need to have every link in the chain the best it can be, but I think converter quality is really to high already to worry (obsess) about.
So in my opinion the ADI2pro+ = the babyface pro. Or if you want best DA per se, get anything plus the ADI2 dac.