You hear the term "texture" thrown around here when people talk about the Alnico driver and I think that's just a great description. Compared to the RS5 (and any conventional speaker I've had in my room), the Alnico has the ability to convey more information on just about every note that comes out of the speaker. It also goes lower, and can play louder without sounding pushed.
On the negative side, for me, the Alnico has a very narrow range in the upper treble where it's brighter than the RS5. You can affect it quite a bit by adjusting the driver position (both vertically and horizontally) in relation to the listening position. I wouldn't be surprised if the RS5 measured flatter in the higher frequencies on axis. You don't hear it very often, but when you do, it stands out because the Alnico is so refined and smooth. Is it the speaker or the recording...I don't know. Of course the RS5 has that speed that it's known for. There's a "snap" to the RS5 that you don't quite get with the Alnico. It might be simply due to the fact that the Alnico's lower response makes the speaker sound a little heavier and slower.
I love both speakers and if one was taken away and I was forced to live with the other, I'd have no problem with that. I definitely prefer the Alnicos, but the RS5 is a worthy competitor. I have a small listening room and I'd bet in a bigger room, I'd prefer the Alnicos by a wider margin.
Last thoughts....for me the Alnico is less suspect to amplifier variations. I must have at least 5 or 6 amps laying around here and I throw them all in from time to time. With the RS5, I really only love it with tube amps. With any solid state I've thrown in, it just loses some magic. While I prefer tubes on the Alnico as well, it handles solid state better for me than the RS5.
Hope that helps.
