I want to thank everyone who posted for their very thoughtful and wise guidance! If my Basis turntable supported two arms without exorbitant expense I would have gone that route. @elliottbnewcombjr I am very envious of your setup. You have quite an amazing custom turntable. I had read your discussion on two-tonearm setups, but felt it best to go the route of two tables rather than replace the Basis which continues to serve me well for stereo records.
@lewm your post made me realize that while I can't spring for one of the multi-arm beauties on the aforementioned thread, I should aim to acquire the best headshell-replaceable table that my budget will allow. From my research, that seems to be a Technics 1200-G. I'll have to wait a bit because they seem to be back-ordered on all the online stores. I have been using the mono button on the McIntosh preamp and never really noticed much difference in sound. Perhaps the button was faulty or I'll find my journey leads nowhere besides having some options for cart swapping that I lack today.
@dogberry I am intrigued by your conversion of the Benz Micro Ruby 3. Did you own that new or buy it with the plan to convert it to mono? My first "audiophile" cart was a Benz and I've returned to the fold with the recent purchase of the Gullwing to replace a Hana ML. The retipped Hana will now be my lower-quality stereo record cart on the new table. I usually play records about 1,200-1,500 hours per year. Wouldn't want to burnout the Benz unnecessarily on unworthy records. Had you considered or owned other mono carts before the Ortofon?
@danmar123 I wish I had posted my question before sending in the Hana ML for a retip. It would have been interesting to purchase a new one for lower quality stereo play and see if one of the retippers could have switched the old one to mono the way others described here. I know that Hana offers the SL mono, but haven't seen an ML mono version. Does anyone posting here know if an ML can be switched to mono or is the SL likely to be the better choice?
Again, thanks to all for the great advice. You have provided me a very valuable education on factors to consider for my entrance into the multi-cartridge territory!