From what I've heard, it's true that the E30 has not been competitive in ITS for a long time - not even fully prepared for ITS (rather than Spec E30).
But if you're a rookie like me and you want to get seat time + racing experience, there is no reason not to run SCCA. In fact, I think the popularity of Spec E30 has caused some spillover into ITS. At a recent SCCA PDX event, I ran into two E30 owners who are planning to run ITS next year.
I'm trying to build a hybrid ITS/SpecE30 racer myself. I figure as long as there are people to race against, it should be fun. Being near Summit Point, it helps that they run almost the entire MARRS series there. If I improve over time and feel the car is a disadvantage, then I'll have to either switch cars, prep for GTS or KP or whatever, or stick with SpecE30!
I heard a
vague rumor that SCCA may consider reclassifying the E30 at some point. I'm not holding my breath since they move at a glacial pace on that kind of thing, but who knows?