I have the small blue plastic brick, and the large one.
They differ in sound – the small is very ‘springy’ for want of a better word – you get the characteristic sproing with attacks.
The large one is more mellow, and while it’s not much longer in decay than the small one, it is longer.
I have the small one inside my case, and the large outside it. I did have some issues with noise, but once I shuffled the small brick and the module in my case a bit, I got it to be so quiet it doesn’t bother me at all. Some positions of the brick/module did result in quite a bit of noise, so that’s something worth taking into account.
I really like the EQ – sweeping it with narrow bandwidth settings is really nice, as you get these phaser-like sounds. Also the feedback is fun.