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 doubles the cost of the Melanger.  I was also wondering about the CocoaTown Melanger in the same price range $500ish.  Does anyone have an opnion on which of these Melangers might work better or achieve a higher level of results?

Thank you for any input you may have on this topic, it is much appreciated!

Best regards,

Catherine Policella