1.
I reported a long time ago that there is a flaw in the engine (via forum and tech support). To sum up, at times it's not sample accurate when you record something.
http://forum.ableton.com/viewtopic.php?f=2&t=103857
2. I found out that this is the case with the new fade-in system too.
When you record an audio file, it's sometimes not identical, not sample accurate to the source. Just do a test like this:
- record an audio sample which has "fade on" to another track
I guess you get what I've done out of the picture

- I checked if the recorded file is identical to the original one with an inverted phase test.
- I don't get silence, therefore it's not the same. When you add or subtract 1 or 2 samples delay (as +1, +2 and -1, -2) you have silence.

I haven't figured out what's exactly the reason for this, because sometimes I don't have this problem. It's a bit strange and I don't know if there are similar problems in other parts from the program.
You may ask why 1 or 2 samples delay are a problem, just hear the sample:
- snare hit 1, 2 are added sample accurate.
- snare hit 3,4 are added with 1 sample delay.
http://yshare.de/index.php?h=a7ec007c31 ... 5f0bf7971f
- snare hit 3,4 are muddy and have a lack of attack when you compare them.
In a serious DAW this kind of problems shouldn't happen.