Today was not very successful for me.
I decided to remove the old Mono installation, and Picoscope as well, and make a fresh install of both.
I followed your link and installed the Mono first. And it's 197MB to download, but it occupies 599,6MB on disk. That's where I got the number from.
Then I downloaded and installed Picoscope 6.11.6 again, but now it won't start at all. It's complaining that there is no Mono installed.
I check in the Mac system information and Mono is listed under installed Frameworks; it's there all right.
So I remove the Mono again (and it no longer show up in the Mac system info) and then reinstall it (and it's back in the Mac info).
But picoscope still won't start.
Where to go from here?
The version of the Mono that I installed is: MonoFramework-MDK-18.104.22.168.macos10.xamarin.x86
When I get it running again I will gladly post (constructive) feedback on my findings thru the channel you adviced.
I've now upgraded to OSX 10.11 (el Captain) and downloaded the newer MonoFW "MonoFramework-MDK-4.2.0.macos10.xamarin.x86". However, PS6 still can't be started directly with the app.
But, thank's to a comment by R. Schmidz in another thread, with a small "Automator script" it starts properly:
Meaning, I'm up and running again