@gwng8 As noted on the website, all the drivers are "upgraded". The woofers go from Eminence A's to the B's. And so on with the other drivers. Larger magnets on the on all the paper cone drivers. The upgraded crossover is standard on the SE's. That's about it.
But what does it really matter. The question is how do they sound? Buried in this thread is commentary by owners who lived with both models. Don't assume the SE will clearly outperform the base DI in all situations.
Eric rarely responds to emails. It's a miracle he can even take any calls. No doubt he will be multi-tasking if you get a hold of him. Try a Saturday am. Research things on the web.
I own the base DI's and have never felt the need to upgrade--a great speaker. I also have the Electron SE's in another system. Amazing full range speaker in a smaller format. I suspect the jump from the Electron to the SE is a larger measure of improvement compared to the DI to the SE. Both of my speakers share many commonalities--full range performance, wonderful smooth and detailed voicing, and the ability to create a large soundstage in three dimensions. Hard to go wrong with the majority of Eric's speakers.