"Sabatti rover tactical" rifle has MRR barrel (multi radial rifling), which is very similar to this type what you are referring. (search on google)
I did measure once, velocities of that sabati rifle, (308 win) and velocity of factory ammo, were somewhat higher then I expected. (that rifle belonging to a friend).. I forgot real numbers but if remembering correctly, velocities were higher somewhat beteween 50 to 75 feet/sec.. But I remeber that I was surpirsed.
But i had no chance to compare... with other rifle with same ammo.
At this moment, I am strongly allowing for this option, lets put it this way.
When I get a chance I will compare velocities of same ammunition of this sabbati, and other rifle with conventional rifling, with same barrel length. Then I will know for sure.
So, bottom, line, there is a good chance for higher velocities in polygonal, P5, or MRR rifling, which in that case may indicate a smaller frictions, reduced pressures, reduced barrel wear and tear, etc...
But, for "special steel" I have doubts.
Special "tougher" steel, with reduced wear and tear, would need "special tools", or whatever is needed to make the rifling, chambering, etc
To make new tougher steel, with various alloys, it is probably doable, but for rifle barrel it would require investment to develop special tools. Not cheap.
On the other hand, other "plain and simple" barrels of good quality, can be bought for acceptable price, and the rifle can be re barreled for affordable price.
So, I dont think "new steel" will approve its price. But then, what do I know? technology advances every day... I might be wrong on that.
In any case, "new steel" must be profitable, not only better in theory. If it pays, it stays, right?