How are we wiring our Mono systems?

Mastering for mono is not the same as just summing a stereo mix, so mono versions of albums can sound dramatically different from the stereo version.  In the early days of stereo, it was often the case that the mono version sounded much better--it took some time before engineers mastered the art of stereo mastering.  For example, in some respects the Beatles mono versions sound better than the stereo versions and that is even more decisively the case with some Cream albums.  I have some Cream CDs that have both stereo and mono versions, so one can make an instantaneous comparison, and the mono sounds better.  

Turning a stereo mix into a composite mono version is truly a crapshoot, particularly with more recent recordings.  No one masters recordings these days with any consideration of how it will sound when played on a mono set up.  Still, the sound can be surprisingly decent.   

Some of my best jazz LPs are in mono, because the greatest jazz artists were at their peak performing years during the 50s, prior to the big change over to stereo. When I play a really clean mono LP of high recording and pressing quality (using only the mono switch on my preamplifier), I can often becoming completely oblivious to the mono v stereo conundrum.  I agree with Mike Lavigne about the issue with comparing mono to stereo using two different cartridges, one for each mode. So even though I do own a decent mono cartridge, I have never used it.

Larry, I own both the mono and stereo LPs of June Christy, "Something Cool", on Capitol.  Like you say, it is quite evident that these were two entirely different studio sessions.  In some cases she even sings the same song differently.

I am using a mono cartridge (Lyra Atlas Lambda) in my stereo system. My mono albums sound fantastic that way, and I really don’t understand the point to building a dedicated mono system. What does that accomplish that I can’t get with what I have?

I lot of times the mono versions of early stereo recordings are desirable because some of those early stereo mixes are just really strange (like Dylan’s early solo albums with guitar, harmonica, voice mixed L/C/R as if there are three performers).