If reciprocal links with relevant sites is part of your optimization strategy than get linksmanager and exchange links with linkpartners sites.

If you prefer to build natural links through e-mail requests for non reciprocal pages (non directory links) then you don't need linksmanager/linkpartners (they are the same company).

Links from non directory pages are always best, but reciprocal link directory links can help your search position if you have volume (100's or 1000's of individual links).

I prefer one way non reciprocal links, but those are the hardest to find!