specs for 4130 and DOM are the same these days...
SCCA really wants people to put .120 wall of whatever they decide...They no longer appreciate the strength of 4130 to the point when they used to accept 1.5x.095 4130 = 1.5x.120 DOM.
4130 is strong stuff...hard to break. In an accident the DOM will give before the 4130, however, the 'give' might be the difference in preventing your bones from being rattled. It's a subjective issue. I have always used 4130 when building...but i'm done building.
Give me an email if you have any questions.