Thanks for your replies. I was a little surprised the difference between the 2 mp3's were not noticed, apart from the mentioned glitch at 1.36 in acoustic2.mp3.
The split second start of most of the chords in acoustic2.mp3 have this weird like slide effect.
I feel convinced it's due to the conversion BIAB does when making the audio playable as a usertrack.
I'd be interested to know if someone took my acoustic.mp3 and made their own usertrack and experienced the same problem.

Attached Files (Click to download or enlarge) (Only available when you are logged in)
acoustic.mp3 (1.01 MB, 4 downloads)
acoustic2.mp3 (5.4 MB, 1 downloads)