Gas port erosion is a difficult thing to predict the exact effects and when they will occur, because they are related to many different things that may be present with the barrel and the way it is used.
Heat and pressure cause the gasses exiting the barrel thru the gas port in a carbine, to work it's erosion on the port. The amount of erosion is directly related to the make-up of the barrel steel, and also the temperature that the barrel is operating at, much like throat erosion takes place. Rate of fire, ambient temps, and cooling rate, will all play into the equation.
The cooler that the barrel remains, the less destructive the effects will be. Also, any good protective coatings can play a part in this protection.
Since I am intimately familiar with the barrel and the application in question, I can say that this "barrel company" is making a barrel which cools significantly faster than a normal steel barrel, and therefore the erosion will be less than any normal type of barrel to begin with, regardless of any protective coatings involved. Also this protective coating is applied inside the bore, and not in the gas port because of manufacturing processes involved, and none of the barrels from this company are provided with the protective coating in the gas port. However, the protective coating is provided right up to the edges of the port, and is not prone to flaking tendencies like chrome, and this protection of the edges of the port will help to reduce the onset of any erosion of the port, because the erosion will start at the edges.
In addition, the form of gas system that will be employed on this barrel will be of the "self-regulating" type, which expels excess gas pressure out an exit port, and uses only what is needed to drive the piston, according the the manufacturer.
Therefore, it is to be expected that gas port erosion on this particular barrel will be less than a normal steel barrel(or even a chrome-lined one), and that even if some reduced amount of gas port erosion was to take place, the effects would be mitigated by the "self-regulating" mechanism of the gas system being employed on this barrel. As such, I see no cause for worry that this is any problem to be overly concerned with, considering all the factors involved. Nor does the "barrel company" that is being discussed here.
There is no way to totally eliminate all forms of barrel wear, and there is no barrel that won't ever wear out. This "barrel company" has gone to great length to ensure the most wear resistant barrel that they know how to make, which includes some of the most high-tech processes ever employed in barrel making history. If anyone can show me a barrel which will exceed this one under discussion, in terms of an overall barrel package of weight, cooling, shooting performance, wear life, and price, then I'd be very interested in seeing it.
If a "totally wear proof" barrel is what was wanted in this particular application, there is no such thing yet devised, and the "barrel company"in question makes the closest thing to that which has ever become available on the open market.
I hope this is helpful.