Actually, I've had RECENT experience with McIntosh ML-series speakers, having among other things, restored a pair of ML2-Cs for a customer.
I don't know where anyone would get off calling them "all off-the-shelf drivers"... the midranges in those were custom designed by United Audio for McIntosh, the woofers were either built by CTS or by McIntosh themselves (fairly quickly went to in-house manufacture). The cone tweeters were Peerless units... but in that day, the Peerless TO225 cone tweeter was one of the VERY BEST behaving tweeters at any price. Flatter than a 2405, in fact, and went higher to boot.
My experience with listening to the freshened-up ML2Cs, was that as far as bass clarity and extension, there are VERY FEW speakers of any price or age (new or old) that could give the sort of lowest-octave pitch definition that the 12" woofers in the ML2s could do readily and consistently. One of those systems set up right with the ML101 Environmental EQ can do AWESOME things...
Now, the later stuff (1978 and later) is quite a bit more "generic... but the early gear is VERY CAREFULLY engineered. Roger Russell, the first chief loudspeaker engineer for Mc, has a very informative website, listing the chronology of the Mc speakers. Check it out:
http://www.roger-russell.com/aboutmc.htm
Regards,
Gordon.