With no military background, but from what I picked-up here on FR about the S-300, a full-on S-300 system wouldn’t bode well for any planes or missiles in Syrian airspace.
The longer Putin stretches this out, the better Assad defenses become. I think the Ruskies announced how decent their radars were when they picked up that midnight test of two missiles last week. El Dope would have to be suicidal to attack such a well protected and small area. Maybe we have a counter for it, maybe if we do we should not deploy it here and announce it to the Ruskies.
I notice el dope is now talking quaranteen of WMDs and has moved his rhetoric away from punishing Assad for what he did (or may have done). Putin wins another round. If this were a prize fight, Obama would be taking a standing 8 count while his corner is readying the towel toss.
S-300 is good but not great, the serious threat is how many ya have.
If you have four missiles closing from four separate launch sites, you're in big trouble.
The S-350 is another matter, but it is not deployed in Syria, only Russia.
You are correct. There is a reason why the main radar is nicknamed Tomb Stone.
With a range of 200 kilometers it also threatens a broad swath of Israeli airspace. If these missiles are now moving into Syria the Israelis will make every attempt to destroy them before they are deployed. The Russians know that will be Israel's reaction so it may be this is a provocation.