Rob[atSound-Rehab]
I assume Direct USB Recording and TotalMix have full access and control also over ADAT in/out for the monitor mix?

Yes, you can apply effects to and record with DigiCheck or to USB everything that comes in the SPIDF or ADAT inputs. SPIDF is on the UCX. You can mix it all together and use parallel compression if you use the loopback feature creatively.

Using the ADAT and syncing to my Tascam 2488, I get up to 24 concurrent tracks.

I still wish I had purchased the UFX though.

It is true that in 1u I can record eight channels with the UCX and the quad Mic pre. With the UFX alone you can only record 4 channels with only 1u. Of course the UFX scales up fast.

I went from an Octa-Capture to a MOTU 896mk3 Hybrid (as much as my wallet could stand).
 
Better all around after I had tutoring on their Que Mix.
I always used a mic preamp with the Octa-Capture but find for most vocal the mic preamp is not needed.

From the RME forum: the USB interface of the UFX is limited to about 10 MByte/s throughput. Therefore recording in Double Speed is limited to 34 channels, in Quad Speed to 16 channels.
 
I assume this means you can record all 60 channels in Single Speed.
 
And this is with a single 1u unit.

Yeah, but you need converters for all but twelve and preamps for all but four.

You get sixteen in on ADAT fiber.

Four analog in on the front with pres.

Eight analog in for quarter inch inputs on the back... no pres.

The last two are aes digital input.

So practically, to record 28 inputs, you probably will need 2u for preamps and converters to the ADAT inputs. 1u for another 8 preamps to the eight UFX analog inputs. So, you are at 4u counting the UFX.

When mixing live, I would probably copy the live mix to the AES channels and set them to loopback so I could record the live mix for reference later.

Using my RME UCX, quad Mic pre and Audient ASP 880, I get to sixteen channels in 2u. I get to 24 channels by bringing my Tascam which is big and cumbersome. I sync using the SPIDF.

This leaves me no ability to scale up without buying another RME interface. The interfaces can be used together to scale. I believe the limit of interfaces is three on one computer, but this would push the IO capacity of most computers. I believe it may be possible to write the data from each interface to a different drive using RME DigiCheck, but I haven't done it.

Also, at double speed, the ADAT work together so you get half the channels... sixteen becomes eight. At quad, sixteen becomes four. So at quad speed the UFX only handles eighteen channels.

The analog channels are not reduced by going to double or quad speeds.

Also, at double speed, the ADAT work together so you get half the channels... sixteen becomes eight. At quad, sixteen becomes four.

 
That's just the way ADAT works whether you buy a $90 interface or a $9000 one, you loose digital channels with ADAT and MADI at higher sample rates.  The new UFX+ does have MADI capability which should allow for quite a bit of expansion later on, for a steep price of course.  
 
With two ADAT inputs, you can use all the channels of an 8 Channel digital preamp at 96kHz. I rarely record more than 10-12 channels at once even with a full orchestral recording.  
 
And personally, I never record at 4x speeds, waste of space with no sonic benefit IMHO.  

The positive gushing we read about around RME interfaces turned out to be true for me. Low latency, dependable and the surprising thing to me - the sound was much better than any other interface I used to own. Absolutely no buyers remorse, just satisfaction.

Rme