@earther Looks as though there are a number of similarities in our conditions, at least in the arrhythmia department, though it looks as though I may have some other heart issues as well.
I'm not that much younger than you are either, I'm 78, though I'm still kicking along, active and plan to do so as long as I'm on this side of the grass! And I promise you, I thank G-d every day for my pacemaker, it's made that much difference in my life.

I wanted to address your question about the pacemaker "rate control setting", though there are many other settings on a pacemaker that address other issues, and these settings are customized for each patient. The lower rate is set on each pacemaker, this is the heart rate at which the pacemaker "kicks in" and sends an electrical signal to the sinus node in the atria ( and may or not send one to the ventricle as needed) which begins the next heartbeat. The default lower setting is 60 BPM, though this can be adjusted for each patient, the lower rate setting prevents the person's heart rate from going below whatever the setting is. The higher rate setting is the rate beyond which the pacemaker will not pace. That is also adjustable and varies with the person's activity and other needs. This upper rate will be higher for a very active person, higher than for a couch potato, and like all the adjustable settings on a pacemaker sometimes requires some trial and error to come up with the optimum settings for each person. My rate settings are 55-120, yet my daughter, who also has a pacemaker and is more active than I am, has settings from 75-175. These were set for her over some time and trial/error and she's happy with those settings. My upper setting was set rather low to avoid any overlap with an alarm setting on my pacemaker which notifies the pacemaker clinic if my heart rate goes over 140. With the rate settings, your heart won't go below the lower limit with the pacemaker, and if the heart rate is above the upper setting, it's not the pacemaker it's your own heart pacing itself ( or maybe a tachycardia, but not the pacemaker normally).

The rate response setting is also variable, depending on the patient's needs and activity. Some people don't need it, don't like it and for them it's not turned on. It's primarily used for patients with chronotropic incompetence, ie, their heart rates will not increase enough to support increased activity. This is another trial and error setting as it's hard to just select a setting when you aren't sure what's needed to support a patient's activity. Mine's worked out well and overall I'm happy with it. My daughter, on the other hand, had several visits to her cardiologist/pacemaker clinic, and they had her run on a treadmill to find the optimum settings for her, and sometimes that is what it takes. There are a few tradeoffs, for the rate response, though. Depending on the make/model of pacemaker, how the rate response works varies, and my pacemaker is a St. Jude Assurity model, and the rate response is a mechanical device in the pacemaker that responds to movement. So if I drive over a bumpy road, rock in a rocking chair, or sometimes when I flip over to my right side in bed at night, the pacemaker will pace my heart up to 100 or a little more. If the rate response is set at too sensitive a setting, the pacemaker can increase the person's heart rate too high at very little increase in activity- like in my daughter's case where her heart would be paced up to 120 when she got up and walked across the room. That needed adjustment, obviously, and it was for her. I'm ok with the few increases in HR over bumpy roads and I stay out of rocking chairs anyway ( they make me nauseated- motion sickness) and find those a small price to pay for the great job the rate response does for me.

As for settings with your pacemaker, those will likely be trial and error for you as you find the optimum settings for your activity levels. What can happen sometimes is that an active person may find that the upper setting of the pacemaker may not allow it to pace to high enough a heart rate to support that activity,(thinking of hiking uphill, running, swimming) and the person's own heart can't get that high on its own ( bradycardia). That might just require an increase in the upper rate setting, again, sometimes this is trial and error and they may be able to determine your optimum settings if you're able to run on a treadmill.

I hope this helps a little. If you've got well-documented bradycardia, and some serious symptoms associated with it ( if that includes the blue digits and periodic blindness those are new for me) it seems as though you'd benefit greatly from a pacemaker. In your shoes I don't think I'd hesitate to give your ok to get one. You do need a good cardiologist, preferably an eletrophysiologist (EP) to help you with this, and you'd need an ongoing relationship with a pacemaker clinic as they will monitor your pacemaker ( probably remotely) and make any adjustments on your pacemaker as needed.

I hope this makes sense!