Sending proofs to CRM clients w Zsign

Sending proofs to CRM clients w Zsign

I need to send 150 different PDFs to 150 of my CRM clients.
The cover letter would be basically the same but may vary in 30% of the sends.

Can I use my CRM contacts last to send each of them attached or cloud based PDFs for their review.
Then get feedback/modify/resend or get a signed approval. 

I'd like to know if Zsign is a good solution in users' opinions before I start using the App.

LMK
THANKS