I've been waiting on installing Exchange 2010 SP2 rollup 6 because I don't seem to have any of the issues fixed in RU6.  I've been successfully running RU5.2 since January (mail site is stable).  I've already installed the security patches in that rollup via windows update and I'm concerned about the 'soft-delete' user issue reported in that rollup. 

My question - should I install RU6 now that I have a window to do it or wait for a possible RU7 (future window). 

I have no plans at this time of moving to SP3 (but probably will in 1Q-2014 before support for SP2 ends), but would that be a better option now that RU1 has been released for it? (Note:  I don't need interoperability with E2K13 because that is not even in the planning at this p

It is always recommended to have latest update and service pack installed even if there's no obvious issue that you should fix. If you, for example, ask for official support from MS, you will be asked if you have latest SP and RU installed. On the other hand, if you miss one RU, you can install next one as they are cumulative.

Final Follow-up:

Successfully applied RU6 replacing RU5-v2.  Ten nodes: 3-CAS, 3-HUB, 4-Mailbox(not-clustered). No problem with KB2506143 because it was not installed (was not installed for RU5-v2 either, but I checked to make sure it wasn't installed via Windows Updates since RU5 install last January. (check nodes with: systeminfo | find KB2506143)

the only other thing unusual about my site is that one of my Mailbox servers has IE10 installed because it slipped past me when I was doing a bunch of security patches in mid-May and I didn't realize Windows Update was offering it to my Exchange Servers until I had accidently installed it on one node.

Similar install time to RU5 - Elapsed about 11-15 mins per node (depends on roles) with an outage of about 6-8 minutes between services shutdown and restart.

Per best practice I also rebooted each node about 30-60 mins after the RU install to verify a successful next reboot. 

My users have not mentioned anything about the soft-delete issue so far and I've also noticed a few non-critical warning event messages that I was getting intermittently seem to have disappeared.  So far functionality seems as good or better than with RU5 but it's early and the systems have not been under heavy load - yet.

Good Bill.

SP3 has fixes for various issues, so it is always recommended to be running on the latest if there are no global issues with those rollups or service packs.