The catch with Scanned Synth Mini is that it only allows new sounds to be programmed through randomisation. Each group of parameters can be randomised individually, but there is no direct access to the parameters themselves.
Scanned Synth Mini can load and save presets through the host application that are compatible with Scanned Synth Pro and vice versa. This means that Scanned Synth Mini can actually produce the full range of sounds that Scanned Synth Pro is capable of. Only the amount of control the user has over the sound is limited when compared to Scanned Synth Pro.
When you decide to upgrade to Scanned Synth Pro, you just install it and Mini will be replaced by Pro in all your tracks without you having to do anything.