g1smd - 6:40 am on Sep 15, 2012 (gmt 0)

301 redirects generated by Redirect, RedirectMatch, RewriteRule or a HEADER directive in PHP all look exactly the same to the browser that made the original request.

It's the module execution order and rule execution order that are crucial here, so you would want to use directives from only one module. So, mod_Alias (Redirect, RedirectMatch) can only do redirects while mod_Rewrite (RewriteRule) can do redirects or rewrites. As soon as you have a single RewriteRule it's time to convert all of your Redirect and RedirectMatch code to instead use RewriteRule.