g1smd - 5:04 pm on Jan 3, 2013 (gmt 0)
I would have added the redirect some time after fixing the canonical tag and fixing the navigation.
Hopefully, you are now pointing to URLs ending with a slash.
Use the Live HTTP Headers extension for Firefox to check the responses for a few canonical and non-canonical URLs.
Run Xenu LinkSleuth over the site and carefully check the reports.
(shtml|html?) simplifies to
Add a blank line after each RewriteRule for clarity.
Should I also put in individual 301 redirects for each category index?
That's what the
(([^/]+/)*) bits are for.