Ok, let me try to be clear here as to what I meant. I did edit my post to 'Playback' latency.
I was responding to how songsj posted about hearing back what he recorded and recording to it. Latency from DAW after recording and processing will be more of a computer performance issue than a interface driver issue.
I am not trying to sell anything. I do not doubt the more expensive Focusrite may be better in some ways than the Tascam's. I only gave my take on my experience with the Tascam's I have used. They did not have poor input latency and the preamps were not bad at all. The Tascam headphone amp left a bit to be desired, but the units I used worked quite well. Yeah, I get much better performance from the interfaces I use now, but more the power of the computer that allows me to run 24 input tracks to DAW, while hearing back 60+ recorded tracks, a shit ton of VST's, and record at acceptable latency. That is all the PC ability in action. Not necessarily the interface drivers...Though yeah, more expensive ones will likely perform better than others.