i have used the Evo 200.2 monos and a 200.4 in bridged mode with my APs, and i think there is plenty of power. they'll play loud without strain, there is plenty of articulate bass, and the sound across the entire spectrum is detailed and controlled. i have no complaints. the only caveat i have is that the APs and evos are both pretty analytical components (no ss harshness, but they choose accuracy and articulation over sweetness). some folks think the combination lacks upper mid-range sweetness and might be a touch dry. i think they reveal exactly what is on the recording without adding coloration, and i'm happy with the combo. but if you're looking for sweetness and bloom, this is not the combo to go with.
i agree with you about low bass in the APs. the libras are supposed to go down to 28 hz. the bass is fast, tight, articulate and reasonably deep, but seems to lack the very bottom end. i have tried them with vandersteen 2wqs, and did not think the speakers integrated very well with the subs (i still use a 2wq with my AP celsius cc with pretty good results). i have been thinking about trying the ap sub, but it's pricey, and i have been focused more on the front end.