After having run Secunia and Sumo for a month, as much as it pains me to say it, Sumo is still king for me. I install the No RK version which avoids installing the Relevant Knowledge tracking software and now that I am aware that they try to install a bunch of other crap, I just uncheck the boxes or decline the installation. Still it's not for novices as it tries to install stuff as one launches the program for the first time.
Secunia seems to be concerned only with releases that are are somehow tagged as security related and doesn't cover all of the applications I have. Bizarrely, it did find an update to Microsoft Core XML services (or something like that). I say bizarrely because one might think that this should have come up as part of Microsoft's Windows updates but did not.