Was trying out these 2 Flash / Flex / Air debugger for a few days and i strongly recommend these 2 applications to any actionscript developers. It allow us to see what the frame rate, flash render time and also the memory consumation of the application we are building.
For the Alcon, there a flash render time (the time flash take to render a frame). This is a very useful information as we should always try to keep it as low as possible in order to maintain a high frame rate. There also code like Debug.inspect to inspect object properties, however we are unable to change it values at run-time.
As for De MonsterDebugger, there no flash render time being display, however, we are able to change the properties of our array, object, movieclips, etc properties at run-time. This can be quite handy for fast tweaking.
For those out there who are paying more attention and focus to optimisation and streamlining of flash / flex / air, you will need to check out these 2 applications.