Gaius,
there is a serious issue with -Txhtml using the current CVS:
Whitespace is swallowed either before or after an equation. Consider
this simple input
.EQ
delim $$
.EN
A $a$ B
with -Thtml you get
A a B
but -Txhtml produces
Aa B
Even worse, sometimes characters are swallowed too:
.EQ
delim $$
.EN
A.$a$.B
gives correctly
A.a.B
with -Thtml, but -Txhtml produces
A.a
Finally, grohtml confuses paragraphs; as an example you might try to
process the groff_diff man page (with -Txhtml) and look at description
of the `Dp' and `DP' commands (in the `Drawing Commands' section),
comparing it with the output of -Tps.
I suspect that all those problems are incarnations of the same bug
which I hope you can fix easily.
Werner