I have done that, tested the 2.12.0-1 version currently in unstable, and
believe it to be the best and most supportable version for Lenny. I'm
asking that this be allowed into testing, since we're still early in the
freeze.
Below, I've provided references to bugs fixed in the 2.12 version, which
would be present in 2.11.2 currently in Lenny. None of these is
release-critical, so I can't argue the case on those merits. OpenHPI
(libopenhpi2) has only one rdepends outside of itself: heartbeat.
Therefore, the risk to other packages is minimal.
From my perspective as a package maintainer, the most important reason
to update to 2.12.0 is to have a supportable upstream version.