Take a look into erpnext or odoo. Two different products, Python/web based, paid support, and a a lot of users.
Gnucash or Kmymoney.
I used to hate gnucash but I have basically become an accountant with my own life. For businesses it can definitely be used for minimal crm tracking and invoices.
I love Gnucash but I am not sure that it is the best tool for remote/distributed work since it cannot be used by multiple users concurrently without corrupting data.
I understand the allure of it, but why would you want multiple people manipulating an accounting like file at the same time? That seems like something complicated enough that you wouldn't want multiple people in it at once.
In a bigger environment you'll have more than one person handling payments, contracts, commitments, ...
Ahh yes now I get what you mean. I guess I didn't think about it like that. I was just thinking like a simple small business.