Brian,
Rob pointed me to a benchmark of MySQL vs. Tokutek which is interesting
to your case:
http://www.mysqlperformanceblog.com/2009/04/28/detailed-review-of-tokutek-storage-engine/
It's also interesting to me because apparently InnoDB *does* have an
issue with large numbers of inserts to an already-large table, which we
don't have (I don't think we do, anyway).
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com