Axiom prices tend to be higher than other brands, but what you're getting is neutrality. You can be confident that they didn't intentionally insert a lifted top end, mid-bass warmth, or exaggerated midrange. Those effects are pleasing and sells speakers on the showroom floor, but are fatiguing colorations.
I have the M5HP, and in comparison with my Kanto Yumi and Angstrom Omega II 200, I consider it to be the most neutral of three very good loudspeakers. I haven't heard the other Axiom bookshelves, but I'm confident you won't be second guessing your decision. I'd factor in the cost of a compact subwoofer in whatever you choose to get.
