Indeed, another good question....
That would depend on your computers performance. I had 60+ tracks running, plug in effects more than probably necessary, while monitoring through Cubase (computer output) and
US 1800, and recorded new vocal tracks with less than 10ms of delay. But then, I built a computer that does nothing but record. It not really the interface that causes latency. Some perform better than others in this respect, but it all comes down to your OS/MB that makes things happen smoothly.
If you have a slower computer setup, then latency will be an issue. It is not so much the drivers or interface, that you need to address. Never had a issue with the 1800/1641 with my setup. Though my PC was built to do what I ask of it.
Direct monitoring of the inputs with the 1800, is workable. Though you are dealing with a knob, that controls the mix of playback tracks, as well as the live recording track. No effects, nor volume control over the input signal. I have found that trying to listen to a direct signal while recording, is not beneficial for me. That is why I upgraded/built a computer that can handle playback through Cubase, and not have to worry about all the latency crap.
I upgraded to
UR824's, which have their own DSP effects, and also have two new
UAD-1 cards, that should allow me to get close to zero latency while recording.
Again, I really didn't have a problem with it before. It is your system, that will make or break your latency issues.