This article cites Al Quds, same as the previous one. Why would it be more reliable?
Again, I'd wait for Rosoboroneskport to confirm it (remember they confirmed the contract with Iran), or for photos to surface. An S-300 missile site can be spotted from google earth. And there was a blog somewhere that detailed locations of thousands of SAM sites around the world. So S-300PMU1 sites would likely be located.
If the missiles had indeed been delivered, Israel, and the West, would know about it from satellite imagery, and in-country intel sources. So the greatest value of these assets would be as a deterrent. Meaning the best way to use them would be to advertise their existence, while concealing the locations for their deployment. Instead we have low-level internet newspapers reporting on the deal, while Russia is denying it. Given that the time frame for deploying the systems, and training the crews, is months rather then weeks, they'd have to have prepared for this well in advance. And here's a better question for you, why would warships deliver them? Never-mind that there is no transport in the "CVBG" that Russia has in the region. Why not (if they wanted to keep this covert) deliver them in unmarked civilian containers? Russia delivers plenty of weapons to Syria, it wouldn't be hard to conceal the S-300 delivery, as a (widely advertised) Bastion-P delivery. Instead, the article claims it was delivered by Russian warships. It sounds like somebody decided to combine two rumors "Russian warships protecting Syria" and "Syria has S-300" for extra believability.
I'd wait and see for real evidence. That having been said, such deliveries are not at all impossible. Algeria got S-300PMU1s, and Libya was about to when their civil war broke out. My main point is that we have little (if any) to suggest that such deliveries have/are taking place.
