Is SugarCRM "enterprise ready" ?

We are considering options for replacing our existing CRM package with something newer and more flexible and SugarCRM's name came up. However, I am having a hard time finding detailed information comparing Professional and Enterprise. I also don't see anything that details the administrative controls that the CRM admin has - about customising web forms, databases, etc.

Is Oracle 10g supported?
Do you do better pricing for larger volumes of users (200+) ?

The Case module seems very limited and looks "flat" - just company and contact - is there no LDAP stype hierarchy, e.g. Customer or Company / Site / Contact ? Is there an ability to easily customise this? Would it be easy to add case notes to track a conversation on a case. Can it trigger events / emails when things happen to a case (status change)?

I see there is no email integration at present though another thread talks about POP3 checking - IMO, this isn't "enterprise class" at all - you would need to provide realtime inbound SMTP with attachment extraction and filing (for example). Tho this isn't a huge concern for me as I know I can code it myself (I built the SMTP integration for our current peoplesoft install).

PHP is appealing as I have 9 years PHP experience - however the demo really doesn't scream functionality to me. It looks pretty, but eye candy with no backbone will get me fired I really could do with some details on admin/management of the app.

Thanks for taking the time to respond.

Paul