Morning Robert,

You've touched on my latest fascination.🙂
With your collection of albums you should try it!
I would say for me it has been worth it. I have had a second dedicated Thorens (125mk2) table setup with a mono cartridge setup for about 3 months now and I love comparison testing and have really enjoyed using the mono cartridge with older mono jazz albums. 

What I found with the cartridge (an ortofon 2M mono, nude spherical) is that older mono albums really come alive but newer mono albums the difference is minor. Older albums (pre 1970) have considerable less surface noise and the spacial feel of the music was much nicer with the mono cartridge. Also more forgiving of warped and scratched albums and it tracks really nice. Newly released or re-released mono albums more showed the difference in a sound stage presence with the mono cartridge than on a stereo cartridge but the difference was very slight.

The Y cables with a stereo cartridge seems to be good enough for me if I were only listening to newer released pop albums in mono.

I have less than 50 mono albums, mostly jazz and blues with a few deutsche grammophon classical. Pop albums in mono don't pop open as much as the live jazz or symphonies do. If had more quality mono albums, especially quality classical albums, I would most likely always have a mono table setup.

You aren't limited to the BG3000 for mono either, you could play with a Y cable on the later Beograms but you won't get the benefits of decreased surface noise (The radial TD125 with a stereo cartridge and Y cable didn't track abused records as well as the mono setup but the Beograms track damaged records great already).

Soundsmith offers true mono on most of their non-B&O cartridges which are pretty much B&O cartridges with different compliance held in a housing so I'm planning to ask them to make me a mono cartridge for my BG8002 once I am done with my Ortofon 2M mono, this would give me ease of switching out for mono albums without having a dedicated table. Although, the PRAT qualities of TD 124 I had the pleasure of using for awhile coupled with a low compliance moving coil mono cart (like the Denon 102) could be beautiful! The choice of which mono cart to try with the BG3000 will depend on which arm you have.
I'm excited to hear your experience if you try this out.

All sorts of thanks and high fives, Peter! Your answer really hit the spot. 

Your description of what a mono pickup does in combination with older mono albums has made want/need to explore this.
And since I'm about as tech savyy as your average fence pole (Y cable?!)  I think a permanent mono table is the way to go for me. 

One of my setups is BM8000, MS150, BG4000 with SMCC20CL+ and BG3000 with what I think is a ST/L9 arm and SP12 pickup. So if I can find a mono pickup to go with the 3000 I think that'll be the most user friendly option for me. And I like the fact that the Thorensgram is more period correct when it comes to mono. 

So then it boils down to this: is there a B&O mono pickup that will fit the 3000? Or, what are my options considering I want to keep the original arm since removing it will turn the 3000 into more of a regular TD124 mk2. 

Soundsmith just responded to me saying that they can build their B&O cartridges as a true mono for an additional $75, pretty cool! I can give you more of the info they sent me if you want it. If one were to use a B&O to 1/2inch adapter for standard turntable this would be cheaper than comparable mono carts from other companies.

I have also emailed the 5 B&O cartridge re-builders I know of about to see if they would rebuild a cartridge as a mono and also about the SP 12 as mono.

Are you using the lightning struck BM8000?

Frede Kristensen of Classic-Audio will rebuild the SP 6/7, 8/9, 10, 12, 14 and will use an appropriate diamond for mono, 25u-17u and make mono at the pins. He will can use what B&O used for 78 rpm mono records with a 75u diamond. With his expertise on the BG3000 Thorens, this is probably the best option.

Let me know if you need more info.

Excellent! I've poked around on tonabnehmerservice.de to see if he can rebuild my SP12 into a mono cartridge, but I didn't get much wiser. So I'm looking forward to hearing the replies you get! 

Sadly, no -the lightning struck BM8000 is in the bin and had to be replaced with the BM8000 I had in my main setup. So now my main setup is BM5500 and BG8002 with MMC1 and penta mk3's. And I won't lie, I miss both the sound and the looks of the BM8000 and will get another one when one eventually pops up here in Norway, but the more I fiddle around with the placement of the pentas the more I appreciate their midrange, highs and soundstage. 

Frede might be the common sense option, no doubt. 

It would be great to hear what the various rebuilders report back to you, not to mention which route you decide to take and your thoughts about the results. 

Next option, Audio Origin out of the UK responded stating that they will make the cartridge mono for a small fee when repairing a cartridge.

I think a mono pickup will be my christmas gift to me this year. That should give me both the pressure to actually make this happen + give me enough time to be able to sort it.