Share 'Speed Control Option for Santha Spectra 11'

I am getting ready to try my hand at making bean to bar chocolate.  I am considering purchasing a Santha Spectra 11 Melanger. There is also an option for a model of the Santha with an added speed contol.  Can anyone advise me if I should purchase the model with the speed control?  Will this make a better product, what are the benifits to this?  The cost of the speed control option practially doub…