Since you already have ER18s, why the statements?
When I set out to DIY speakers, I was to cover multiple bases and budgets. From large and powerful, to small and surprising and trying to stay away from designs that dominate the mainstream, if possible.
It's been the little buggers that have ended up being the most intriguing and adaptable. Currently looking at some coaxial and full range driver builds to cover other territories that I can't just up and buy easily at some box store or just another take on something that is mass produced.
I had seriously considered the Statements, but I'm not lacking sound quality with the kits I have chosen that use less expensive drivers and without having to rely on much by way of cabinet trickery. If my living spaces were difficult, perhaps, but with modest sized, rectangular rooms, standard ceiling heights and an abundance of cozy furniture, less ends up being more. In other words, it would irk me if I built a pair of complex cabinets and ended up EQ'ng out the benefits to something with the sonic signature and capabilities of a smallish bass reflex or sealed speaker.
Some observations with my rooms: I have tried two different pairs of small, full range driver speakers with a subwoofer. One that uses an array of 4, 1" full range drivers in a tiny ported enclosure. Another that uses a single 2" driver in a small sealed box. While these are not optimum with regard to SPL, they have shown that my rooms are very compatible with these types of speakers. Incredible, perhaps profound, midrange translation in this space. This is also what is piquing my interest with coaxials. Between the constant directivity designs I have tried in here, along with the FRs, a coaxial with a 90 degree dispersion pattern might end up being very good indeed.
I'd like to think my perception of high performance audio qualifies a need for exotic drivers and cabinet magic, but it would also tickle me to have a single driver in a simple enclosure end up kicking mine, and everyone's ass that walks in here. Based on the truly custom option that DIY can provide, that sometimes resides outside of what's ultimately popular.