This is a bizzare selection of two totally different sounding loudspeakers with completely differnet personalities.
Harbeths are known for a rich midrange, a polite treble decent imaging and are respected for being musical and natural sounding loudspeakers.
Rahido are known for incredible detail in the treble, a lot of air, a clean but not partiuclarly warm midrange, and good but not particularly low bass.
A Rahido X1 would sound brighter, and smaller than a Harbeth which woluld sound, bigger and fuller and somewhat less detail and sparkle for details.
If you like Harbeth you would most likely hate Radiho, The real issue is what are you trying to accheive and perhaps changing your components might be a better investment.
You need to hear the Radiho to see if you like that type of sound, I am willing to bet if you like your Harbeths you will really not like the Radiho, howerver, if you are looking for geater clarity than a Rahdio might be your ticket.
If you are looking at uber monitors depending on budget and you are looking to gain more detail then look at Rahido, the Focal Sopra 1, the TAD ME 1, KEF Ref 1, and the Persona B.
Dave and Troy
Audio Doctor NJ