Recently, I have migrated from WHMCS and faced a huge amount of issues.
The biggest issue is mentioned in this thread and I was unable to change the module. I have round about about 200+ services on Universal Module but they were on cPanel/CWP in WHMCS.
So, its a headache to
Inactivate/Restrict the existing package
Copy the package, make it activate and add the correct module
Cancel the Service (with universal module)
Manually readd the service with new package (with correct module)
In WHMCS, we can simply change the package which automatically change the module. It will be great if Blesta can change this mechanism.