After switching to modular xorg, things have gone pretty smoothly -
except firefox can no longer invoke acroread5 properly; when it tries,
the following message appears:

/usr/pkg/Acrobat5/Reader/intellinux/bin/acroread: symbol lookup error: /usr/pkg/lib/libICE.so.6: undefined symbol: __sF

It appears that this is the same problem that occured back in March -
namely, http://mail-index.netbsd.org/pkgsrc-users/2007/03/01/0000.html

Any ideas why it's recurred? The same fix works - unsetting LD_LIBRARY_PATH
in /usr/pkg/bin/acroread[5] - FWIW.