I don't know what kind of problems the folks above had but I have been running the pro 40 for a couple years, it is hard monitoring so there is virtually no freaking latency, the pre's are pretty good for the price-point, and if you/I/we/anyone in this price range is looking at products in this price rage it also means that we haven't been doing this long enough for a pretty decent product like the saffire pro to be the weakest link in our chain. It is far more likely that the weak link is the inexperienced ears behind the console not the gear running into it. I have learned that as you climb in experience you start to learn more about what you want from your next equipment purchase. and even if it is a fairly poor choice purchase... it will carry you until you learn why it was a bad choice, what would be a better one, and then move on.
The pre's are cool, latency is nonexisitent, and it has 8 analog in's. Does that fit your needs? Grab one. by the time you find any flaws in it, you will have learned it, loved it, thought it mediocre, learned what you want next, and be ready to move on. BTW, it will probably still be operating fine at that point.