Well, hell, that was painless. After seeing all the horror stories I put off upgrading to BI5 until now. Following the advice here from @bp2008 it went much smoother than I expected, in fact I did not have a single issue. I set it back to "run as service" after upgrade, UI3 works, Android app works, BlueIrisViewer (java app) works - couldn't ask for a better experience. A big thank you to all you brave people who went through the pains of upgrading early on and helping iron out the kinks. I will add that I haven't uninstalled BI4 and don't plan to for quite awhile.