McClellan, Robinson. Pibroch Rhythm: Translating Early Gaelic Bagpipe Music in the Twenty-First Century. Yale University, MMA. 2007
This is an interesting thesis endeavoring to understand and analyze pibroch rhythm.
The full thesis is here.
Supplementary analytic examples are here.
Dr. McClellan has composed a number of choral and instrumental pieces, including pibroch. Visit his site here.