I heard the Genesis 501's in Denver, sharing a room with a pair of forty grand Dali Megalines. Personally, I preferred the 501's to the Megalines, but then I tend to prefer speakers with a warmish overall tonal balance and a relatively rich presentation with good ambience. The 501's impressed me as an un-boxy, relaxing, slightly euphonic loudspeaker.
These Genesis speakers are in a very competitive price range, namely the 10-to-15 grand ballpark. Other speakers in that ballpark that I like include, in alphabetical order:
ATC SCM-100 (disclaimer - I'm an ATC dealer): The big ATC's are smooth and extended with nice midrange, a very solid bottom end, and enormous dynamic capability.
Avantgarde Uno: Very dynamic and lively with very good tonal balance; woofer has a hard time keeping up with the horns but the blend can work quite well with careful setup.
Cain & Cain Studio Ben: Absolutely lovely presentation of vocals and instrumental voices, very natural-sounding, but not necessarily for everyone; not the best choice for very high volume levels or thunderous deep bass.
Classic Audio Reproductions T-1: Extremely lively and dynamic, can reproduce what you'd hear in a good jazz club, probably more of a sheer fun speaker than a polite and accurate speaker.
Eben X-3: First non-electrostat I've heard that can legitimately claim "electrostatic-like detail and articulation". Very coherent also for a multi-driver speaker.
Edgarhorn Titans: Superb all-around speaker, natural tone, very dynamic, but very large. Might be a bit above this price range; I'm not sure.
ESP Bodhran: Very relaxing and easy to listen to long-term with wide sweet spot and good imaging (a rare combination). Well executed design.
Exemplar horn system: Lovely tone and very natural sounding, could listen to 'em all day long, but a wee bit lacking in bottom end.
Horning Hybrid Agathon: Similar to Cain & Cain Studio Ben but with better bottom end and can play louder, almost but not quite as natural sounding (something the Ben's do extremely well).
InnerSound Kachina: Very dynamic-sounding especially for an electrostat, superb imaging, but a very small sweet spot. Nice tight transmission line bass.
Magnepan MG-20.1: Rich presentation utterly free of any hint of boxinesss, and capable of fairly high volume levels, superb pitch definition in the bottom end. Voiced slightly on the forgiving side, which is a good thing with non-audiophile recordings. Big hidden amplifier cost.
Martin Logan Prodigy: Very good all-around hybrid electrostat, small-to-medium sweet spot, very intelligent bass system integrates well with panels. Not quite the low-level articulation of the InnerSounds and Sound Labs.
Shahinian Diapason: A tad below 10 grand last time I checked, but worthy to be considered here. Excellent speaker with classical music, very rich and relaxing presentation, very deep and natural-sounding bass. Trades off precise imaging for enveloping ambience.
Sound Lab Millenium-2 (disclaimer - I'm also a Sound Lab dealer): Similar to the Maggies but with a wider sweet spot, even better low-level detail, but probably not as good on the large-scale dynamics. Very non-fatiguing long-term, but once again big hidden amplifier cost.
The ESP, Maggie, Shahinian and Sound Lab offerings are most similar in presentation to the Genesis 501's. If you like the overall presentation of the 501's, then these are among the competition you might want to investigate.
BIG DISCLAIMER - The above is my limited opinion based on inadequate listening sessions primarily under show conditions with program material that I mostly wasn't familiar with. And I've no doubt left out many many excellent speakers, so don't take this little compilation at all seriously. I sure wouldn't.
Best of luck in your quest!