Firebird supports pooled sequences. But it does not support the standard increment by property of the sequence. Rather it uses a different "next value" function to increment the sequence. Would it be possible for Hibernate to support this? This would allow Firebird to user the new generator mappings with sequences.

For reference:
http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/html/langrefupd25-ddl-sequence.html
http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/html/langrefupd25-intfunc-gen_id.html

An example:
CREATE SEQUENCE sequence-name
ALTER SEQUENCE sequence-name RESTART WITH <newval>
SLECT GEN_ID(sequence-name, <increment>) FROM RDB$DATABASE