Feature:
The Pro-53 can have as many instances as your computer can handle...and it can also out put to 16 or more channels into your software (vst is 16 channels, protools is 32 ch.).

Quality:
I have used a real Prophet-5 and the Pro-53 is just like it...in every way, except that it is software, and offers more control than the original Prophet-5.

Value:
Compared to other software synths that say they do what this does, this is the best value, and it actually is a real emulation of a Prophet-5.

Desirability:
The Pro-53 is a serious emulation of the Prophet-5, every nuance of the original machine was painstakingly turned into lines of code...this thing looks, and more importantly sounds like the real thing.

Sound:
I own a Nord Lead 2, and a JP-8080, both of which attempt to emulate the sound of a vintage analogue synth...after I installed and used the Pro-53, I am seriously considering selling those un-nessecary hardware synths...especially since the sound does not even come close to the Pro-53.

Support:
Most of your questions can be answered from reading the manual, if not try thier web site "FAQ's"...worst case senario, call thier tech support line. I have had to use thier e-mail tech support for another piece of Native Instruments software I own, and they e-mailed me back the same day with a resolution.

Overall:
I can see myself using the Pro-53 for years to come...once it was installed it became an like an old friend to me. I can not wait until Native Instruments comes out with RTAS support for the pro-53...which they are doing this year...they really just know what we want out here in the real world.