As far as what spending more money on a speaker system gets you... less compromise. If you value a system that can reproduce complex music really well then you need something a bit more complex it's self and for the same component quality it'll cost more. But I've also heard some newer "big" speakers do small scale music really well, imo because their "coherence" is improving, when they do play solo female vocals it sounds "right" in much the same way a good single driver does.
So imo if you're looking to move on and upgrade from a speaker like Devore, the real areas they can be improved on is 1. Resolving complex music, and 2. Bass response/quality.... there's no replacement for displacement in audio as well as autos.
If these things don't matter to you then maybe just enjoy what you have until you identify something you really feel would be a worthwhile improvement for you and the music you listen to.