Summary
Some dialects of English truncate; others compress. Finding supports earlier evidence from Swedish (Bannert & Bredvad. Working Papers 10, Lund 1975)
Truncation - a variety specific parameter?
Counterexample: Braunschweig German has truncation in H*L but compression in L*H (Grabe 1998b)
Effect is not language-specific. It is minimally variety-specific and may be accent-specific