Installed-Removed-ReInstalled
I installed the manual roll trim in my -6 when it first became available. Later, I removed it because it just didn't seem to be necessary. Then I began to miss it. It's not totally necessary, but it's nice to have and weighs practically nothing.
BTW, It should have nothing to do with whether or not you have an A/P. The A/P will not be on all the time, and even when it is, you should not depend on it for trim.