First of all, if you noticed the Storage on Mini/JAM/MDA Compact/Magician, you only get a paltry 7MB....7MB out of 64MB!! what the?
WM5.0 uses persistent storage so nothing can stored in the 64MB RAM unlike the current WM2003 devices.
If you look at the current HTC WM5.0 devices like Dopod 818 Pro, out of the 128MB ROM, you get only 35-40MB storage space.
So you do the math, after Mini gets upgraded to WM5.0, how much storage do you get?
-- someone mentioned "what about BigStorage?" you get a total of 27MB after upgrade.
BigStorage is NOT supported by your device maufacturer. In fact, it automatically voids whatever warranty you have left on your device. So BigStorage does not come into consideration at all.