You can also install a test system locally to test your migration, etc.
Just a few specific comments:
Can I send SMS and e-mail directly from the CRM on the account page ?
Email, yes (click on email address, an email compose window opens.). But SMS you will need some integration. You can search the SuitecRM Store for add-ons. You can also develop that integration if it is simple. There are also services that allow sending SMS from Email.
About SugarCRM: yes the core is shared, there are many similarities, since this app is huge I’d have to say that most of the code is still the same. But we’ve made more than 100 releases, so there are thousands of improvements. We also added many important modules that SugarCRM didn’t have, or at least that the free version didn’t have.
And they’re on a downward spiral, we’re growing.
Also, our attitude towards the open-source community doesn’t suck.
I will have Client Account and Supplier/provider Account.
Is it possible to have a relationship between those two ?
Example : My Client Account will order thing on my Provider Account, My provider send me a csv/xls file every month with who ordered and how much. I will have to import this every month.
Is this possible ? Cause its the main activities of my business!
For now SuiteCRM is my best option, I will search if other open-source CRM can do the job too!
Also, you can add custom relationships, so you can make a new account-to-account relationship. But try to use the existing functionality first, before creating new custom stuff - there are advantages to using what is already there.