From my understanding, the Aragon 2005(Klipsch years) is pretty much the same amp as an Acurus 200FIVE, which I currently own. IMO, it is a great sounding amp that really thumps the midbass region and has very detailed highs.
The B&K Reference 200.5 is a beefy amp with very good bass, a warmish midrange to die for, and somewhat rolled off highs which tend to mate better with brighter speakers.
As much as I like how musical my B&K/Klipsch combos sound, I like the Acurus/Klipsch combo better for HT. I moved my B&K's out of my HT system for more music oriented endeavors, and replaced them with an Acurus A250 and 200FIVE.
Both the 2005 and the 200.5 are fantastic at their price points and either will do exactly what it is intended for. While the Aragon will drive most speakers you throw at it, the B&K has a beefier power supply and might be better suited if your speakers are on the power hungry side and often hang around in the sub 4ohm region.
I really like both for the strengths each possess and would not even consider getting rid of any of my Acurus(Aragon) or B&K amps.
Bill