I love this mix, it's almost perfect.
The first part is such a well thought out piece it is sublime, and part 2 is just not quite up to the heights of part one.
Still highly recommended though.
"Boxed" is strictly SQ. What you're hearing on "On Horseback" is decoding correctly. The more recent 5.1 remix, on DVD in the boxed set of "Ommadawn", has more directionality on that track. If you don't have that one, it's worth finding.