The two 8-volt 2005 models are different from one another, as I understand it - the 8445 has a downgraded crossover that, among other things, cannot be run in three-way mode. The 8455 has the option to cross the highpass on ALL channels as low as 63Hz, many more crossover point options (I believe), and the slope can be set gradual or steep (6, 12, 18 or 24db) in all instances.
Yeah, the 8454 cross over blows away that on the 8445.
The 8454 is fixed on a 3 way cross over where as the 8455 can go 3 way, or 4 + 1. The 8454 doesn't go as low as 63hz on the HI channels, only 200Hz. It does on the Mid and Low.