When removing EPS speakers I've noticed the build quality was very good, and the passive crossover is a real 2W 12dB/octave passive crossover. I personally wouldn't bet on them sounding the way I'd like without DSP of some sort - the MS-8 or something else - but I certainly believe they'd sound great with better amplification and tuned signal.
Glad you like the sub! And congratulations on getting so much done on the new car.
Musicar Northwest Portland OR musicarnw.com
High-performance audio for BMWs