disabling OIDs?

The spam filtering package I use (dspam) had a section in their
release notes recently which stated that disabling OIDs greatly
increased speeds, and so they suggested that people do that on their
tables.

When creating new tables, you can disable OIDs with,
CREATE TABLE foo (...) WITHOUT OIDS;
And you can disable OIDs on existing tables by executing for each table,
ALTER TABLE foo SET WITHOUT OIDS;
and then running a vacuumdb (either with pg_vacuumdb or VACUUM ANALYSE;)

Does anyone know of any risks or potential downsides to doing this?

Thanks!

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L. Friedman netllama(at)gmail(dot)com
LlamaLand http://netllama.linux-sxs.org