Steve-O:
I have a DW ECO 9mm. It was good from the factory. I did send it to Matt McLearn to go through, and in my opinion he made it the perfect small carry pistol. 99% of the time I carry it in a leather holster from John McPhee...the SOB Condom holster. Makes the pistol easy to move around the belt, or carry in a lot of different ways. https://sobtacticalshop.com/category/leather-holsters/
The ECO has been 100% reliable. It is accurate, fits big hands okay (it is a small pistol), and it is a pistol I trust.
I would not purchase a new STI.
Good luck!