I find Docusign to be an excellent, time saving product.  The Proseries interface has never worked for me so I can't comment on that (other than to say they took my money and gave me nothing in return).  I made a mistake after sending a Docusign and I was easily able to delete the incorrect document and issue a corrected one myself.

Docusign reps have been more helpful than Proseries reps but can only take you so far before realizing the issues are within the Proseries interface.  I imagine full integration between Proseries and Docusign would be optimal but you just can't trust Proseries to stand behind their products.