ricred1, congratulations on the speaker upgrade! I see Jeff Rowland gear, some nice components.
I beg to differ with your conclusion, "Incremental improvements are very expensive in this hobby." In my book The Audiophile Laws, I discuss how incremental improvements are not hard to achieve. Fundamental improvements are usually more difficult to achieve and may be costly, especially as one climbs the ladder in terms of quality of the system. However, it is rather easy to find fundamental improvements when one changes genre of speakers. Of course, enjoyment of a particular genre of speaker is a matter of taste.
Given the spectrum of speaker designs available, the Monitor speakers are not that different than the YG Acoustics, which I believe is one reason you have concluded that incremental differences are costly. Given a different genre of speakers, i.e., dipole, or full range/concentric, the differences would be pronounced.
In reviewing various models of genres of speakers, it is more difficult to obtain a perceived fundamental improvement by changing speakers when the genre and driver configuration is more similar than if changing the genre and driver configuration. Whether that change of genre and driver configuration is appreciated/enjoyed is another question. :)
Another reason why the two speakers might not sound fundamentally different is because their bass response is within a couple dB. If a person moved from a speaker with shallower bass, i.e., 35Hz +/-3dB, to one with far lower bass, i.e., 22 Hz +/- 3dB, the differences would be more pronounced. Theoretically, a person could change from an expensive bookshelf speaker with shallow bass to a less expensive floor standing speaker with deeper bass and hear a fundamental difference between them. The question would be whether they have overall improved the sound quality.

