Here is an update on the compatibility of SMART Utility with the next version of OS X: 10.11, El Capitan. SMART Utility is mostly functional on El Capitan. However, due to changes in the security policy in the next version the menu extra does not work.
There is a solution but it does involve a lesser user experience. The current solution makes the menu extra behave just like the built in extras- they can be moved around and removed quickly. The new way locks them in to a place based on the order of launching and makes them harder to remove.
Unfortunately there is no other alternative. Bug reports have been filed in the past but to no avail.
Rest assured that the alternative will be implemented to ensure compatibility with El Capitan, despite the lesser user experience. It will be as good as possible however.
Other than that, SMART Utility is good to go. The next version is coming on nicely- look for an update about that soon!