Joomla 3.5
ReDJ 1.7.10

A full URL redirect works (I'm only in a localhost environment currently, not production)
FROM http://localhost/mysitename/forum/user/623-testuser1
TO http://localhost/mysitename/hire/user/viewprofile/623-testuser1
Case sensitive, request only, decode URL all OFF

But a partial URL redirect doesn't - what am I doing wrong?
FROM ^/forum/user/
TO http://localhost/mysitename/hire/user/viewprofile/{userid}-{username}
Case sensitive, request only, decode URL all OFF

I have tried FROM ^/forum/user/{userid}-{username}
I have tried Request only ON
I have tried ON & OFF for case sensitive and decode URL
None of the above work. I have cleared Joomla and Browser caches every time.

Looking forward to any recommendations! Many thanks in advance.

Many thanks for the response Luigi. I must be a slow learner or was missing something fundamental!

I tried multiple options and then revisited your documentation and finally got the below to work perfectly.

^/mysitename/forum/user/
{scheme}://{siteurl}/hire/user/viewprofile/{pathltrim /mysitename/forum/user/}

I'm guessing (will find out when I move to production) that the localhost complicated matters and that in production I will remove /mysitename from both the FROM and pathltrim macro in the TO field?

Many thanks for such an awesome product.