Keith,
With all my respects to your position. It is evident that you have not reviewed the code because the questions you cast to me.
It is in your figertips to do so. Go to sugarcrm.com and then to vtiger.com and download both OS install packs. Install them, review deeply the applications and then make an opinion for yourself.
Plato said: Pryor to have an opinion, it is better to have the knowledge.
Just some hints to your questions:
a) User Groups Managment, Outlook Link, Inventory Management, Outbound Email management, Reports, Invoices, Word Link
b) Just look to what you can download from the SugarCRM website, and you will se where they stopped (too early, unfortunately)
c) For instance: Try to prevent that one CRM user deletes all database in Sugar (this is very basic). I bet you that you won't be able to do so with the open source code from them.
d) Just to tell one: Try to add the 'ASSIGNED_USER' field (a basic sugar field) in a custom designed form. I will dissapear when you save the form. Is this a Harry Potter magic feature? :)

Again, Keith, I opine with the knowledge of having installed and tested bot products.
My guess is that your opinions come from a different side other than knowledge. Do not trust in interested articles. Test for yourself and then have an opinion. This is my humble advice.

;-)
Jose.