Thank you for your message. You are correct the 256MB is the recommended one, but as other plugins also need resources we may be on the safe side to have the 512MB version.
That is correct, Your server info indeed meets the prerequisites, the reason we asked for the test is to make sure there is no other possible problem such as a mod_security restriction or firewall or a factor that we might not have taken into consideration and the best way is to test in a local machine or the other test server.
You are right the Pro also uses the same Ember technology. So we can make sure that the difference between backbone and ember is not the problem on your case.
I totally understand regarding the long thread. Thank you for considering our suggestion regarding the threads.
Yes, I agree and I think we should keep investigating the case as having this intermittent fails will slow down your development process.
The link I provided is the landing page for our hosting service. I suggest that you check our peer to peer forum and ask for the opinion of our customers regarding the hosting service;
One last thing that came to my mind that might be the problem cause and I suggest that we get it out of the way is the PHP Script Execution time limit. The servers usually have it in 30 seconds. Kindly ask our hosting to make it 300 seconds to be on the safe side.