The only problem I see is that you stated that your old URLs end with a slash, but your new rule doesn't comprehend/match that trailing slash.
A minor issue is that you should only use parentheses around a sub-pattern if you need to make use of the sub-string that it matches as a back-reference or if you need the parentheses to 'group' multiple characters or regular-expressions character-match tokens in order to apply a quantifier to all of them. Otherwise, you're just making your server do unnecessary work -- minor in this case, but such things can add up quickly on a busy site, resulting in an early server upgrade being needed.
# Externally redirect requests for old URLS of the form
# /equipment/<unique-id>/<brand>/<product>/<product-id>/<product-id-slug>/ to new URLs of the form
RewriteRule ^equipment/([^/]+)/([^/]+)/[^/]+/([^/]+)/[^/]+/$ http://www.example.com/equipment/$2-$3/$1 [R=301,L]
Using comments to make the code self-documenting as shown here is highly recommended -- both for ease of discussion here and for future code maintenance.
So, for URLs matching the given format, you're down to one rule -- not hundreds or thousands.
The resources cited in our Apache Forum Charter and some of the threads in our Apache Forum Library may prove useful to you.