I think the work-a-round may be this:
1. On the computer: Contacts:Preferences:select vCard: check or uncheck "Export notes in vCards." Just don't forget which you have selected. Otherwise if you share the contact you run the risk of sensitive information being exported. DANGER: If you select the "Share the current card" icon in the lower left corner, the notes go, regardless of preferences. You must export the vCard and then attach to an email to avoid sending the notes.
2. The other way is to share or attach the vCard to an email, irrespective of the preferences setting. Open the card within the email before you send it. Edit out the notes. Send. No effect on your original.
3. On the iPhone: I like that it doesn't send the notes. I can simply copy them and paste them in to the text of an email and include if they are critical. Don't see an easy solution if they are large and you are sending text vice email.
In all cases, before sending a contact from the computer I would open it within the email or message and make sure what is in or not in the notes!
All the best....and Merry XMAS