Removing pitch or roll KE coupling will improve fying characteristics of the plane for all maneuvers.
What happens in KE in your case? Most likely your plane pitches to the belly. What happens if you apply rudded in the straight level flight? I bet is starts diving, doesn't it? Removing KE coupling will help with that unwanted 'dive' with pure rudder input. Beginnign to see the picture?
You should generally shoot for 'pure innuts'--e.g. left rudder input turns plane left, without seeing the nose dive, etc. See here for the comprehensive trimming process:
http://www.wtp.net/DBEST/trimchrt.html. Follow the chart--don't start mixing out KE coupling right away, it's only a small part of the pricess. It takes time but will result in a much, much better flying plane.
Now, trim on low rates may not be the same as trim on high rates. That is, trimming for IMAC may be slightly different that trimming on 3D rates. However, if you are not competing you probably don't care. Just trim for the type of flying you most often do.