I just updated my xcode to 5.1... Installed all the simulators i needed (6, 7, 7.1 ) and can happily debug in each one.
However, the profiler now always starts the 64-bit retina 7.1 iphone simulator. Tried with time profiler, allocations, zombies, same exact simulator. Tried to switch it in the simulator's own menu, tried to restart instruments, xcode, nothing works. The "Profile" scheme has ticked the "Use the Run action's arguments", but doesn't happen anything. Also, didn't change manually anything in the project's settings before or after the update.
Is there a workaround or fix for this issue ?
Any response much appreciated!

I have the same problem as I wanted to profile against the iPhone Retina 3.5-inch simulator. As a workaround I used Instruments from the command line:
where
$InstrumentsTemplateis the path to the profiling template you want to use with Instruments and in my case was:Applications/Xcode.app/Contents/Applications/Instruments.app/Contents/Resources/templates/Time Profiler.tracetemplateand
$AppLocationis the path to the app you want to profile and looks like this:To see a list of all Instruments templates that you can pass with
-tuse:To see a list of all available simulators that you can pass with
-wuse:Hope this helps.