Why would you want mono? I would think you could accomplish that with your system and still have stereo available if you wanted it.
Not at all, the mono releases are not just stereo folded down or summed to mono. They are completely different mixes, and the only ones actually attended by the Beatles. In numerous interviews since then, all four Beatles and George Martin have repeatedly stated that they prefer the mono mixes, and if you really want to hear the albums the way they were intended that you needed them. The stereo mixes were done later, without the Beatles in attendance and often without George Martin there either. Given the prevalence of mono in the consumer market at the time, the stereo mixes were considered an afterthought.
In some cases the differences are striking. "She's Leaving Home" is at its natural pitch on the mono mix (it was slowed down for the stereo mix), the phasey effects on John's voice on "Lucy in The Sky" is so much more obvious. "Helter Skelter" is missing the "I've got blisters on my fingers!" ending, but sonically it is so much more powerful in mono.
Plus, for some of the songs with the extreme stereo separation (think "Rubber Soul" with all the vocals on one side and the instrumentation on the other) the mono presentation is much more direct and far less distracting. And even for the albums with "normal" stereo mixes (Sgt. Pepper, the White Album) I'm finding that I really prefer the overal sound of the mono mixes.