Besides replacing the caps you might want to pull the grills off and take a peak at your drivers to make sure the surrounds are in good shape and not rotted.
Not sure if the woofer or midranges in this series had foam rot problems. your might be rubber and in that case you are in good shape.
The doctor is probably right. the Redline 60 is by no means a bad speaker but the it will never deliver the bass response of your M70. If you like rock n roll then you have the right set of speakers in which case recap and rock on !!!!