At this point we have been unable to get the Update_Tool to run successfully after installing M030. (We are currently on M020.) PTC support has been unable to find a solution to the error so far either. (It's been several weeks.)
Depending on how you use Windchill, there are some issues with M030 that may be show stoppers. See CS210431 (SPR 4493975).
You may also want to take a look at the Update Advisor. Right now it is showing 289 issues reported in M020 that are not yet resolved and another 184 issues reported in M030 that also are not resolved.