I have the Profire 610. Funny story. I used to have a Focusrite Saffire. After I bought the 610 and installed in I reloaded a session (in Sonar 8.5 at the time - have now moved to X1) that I had been working on. This session had around 30 tracks, several instruments (drums, piano, etc) and a ton of plugins. So I decided to try out my new box. I plugged a bass into the DI and armed a track. Played a few notes. Sounded fine. I then set Sonar's input echo to "on" (this allows you to hear whatever effect is on the track, but record dry - and usually increases latency). I actually thought the echo input was not working. I literally could hear no difference in latency when it was on or off. Then I realized it was working fine, there was just no latency. Then, after dancing around the room a bit out of joy, I realized I had an impressive little interface! Far superior to the Focusrite I had purchased. Rock solid drivers. No crashes. And I mean none. Zero. In close to a year. I've had a few software glitches, but nothing related to drivers. I'm sure the Mackie is fine, also. As is the Apogee. But, for the money, I just don't see how I could have done better. Just my opinion. Keep in mind, your FW card, processor, RAM, etc all have an affect on latency, also - as I'm sure you probably already know.