since i initiated the sparrowhawk design and worked with vince on its prototype years ago, and also named it, i think i might be able to answer yer questions.
while i loved the mohawk and it did everything i wanted in a mild r/d hybrid longbow that braced to a classic "D" shape, i kept thinking about a version of the mohawk that was closer to an AFL (american flat longbow, or in essence a hill style longbow).
what i wanted were narrow and thicker limbs, and that's what the sparrowhawk is all about. with its mild r/d, added 5th core lamination and deeper limb cross section, the s'hawk is a tad smoother, a bit more stable, and points easier for me. that's about it! ENJOY! :D