Update, I'm not crazy impressed with these shocks. I found a pretty good set up for 1 up but am struggling to find a sweet spot for 2 up. It's either harsh on smaller stuff or bottoms a lot on bigger stuff. I feel like my stock shocks where as good 1 up but way to weak 1 up. I had 13inch HD premium adjust on my 2013 ultra limited and those where at least as good if not better. In fairness, these are 12 inch shocks but have the same 3 inches of travel. I'm thinking 13's would have been better, but I like the lower seat height.
That's more common than you may think. The more adjustment options you have, the more chances to get something wrong unless you fully understand the interaction between the various settings. IMHO by far the most important adjustment is spring preload, also called sag. Work on getting that right for both single and two-up riding. And it's not good enough to just "wing it" by cranking up the preload a few turns and going for a ride. Actually measure the amount of sag under both riding conditions. Rheiner gave you a good rule of thumb of 1/3 of total shock travel, and that's a good place to start. Since it's not exactly easy to sit on the bike, single or two-up, and measure the shock lengths, making a simple fixture to turn it into a go/no go adjustment might help. One idea I saw that seemed really good was to take some pvc pipe and a couple right angle fittings to make a device you can just slip over the shock bolt heads. Make the tool so that the center to center distance between the right angle fittings matches the dimension you calculated previously, fully extended shock length minus 1/3 of the total travel for example. Then you sit on the bike while your assistant adjusts the preload until the tool slips over both shock bolt heads, record that preload setting (number of turns, clicks, or whatever system your shocks use). Now add the passenger and the amount of gear you will normally carry and have an assistant adjust the preload again, using the same tool, and record that setting. Now you have your baseline preload settings for both riding modes.
Setting compression and rebound damping is more complicated, and hopefully the folks who built your shocks gave you the procedure they recommend for those settings for your weight(s) and how they set up the spring rates. Too much compression damping can cause harshness on jounce and too much rebound damping can result in packing down of the suspension on stutter bumps, for instance. Too little rebound damping can cause topping out and a kind of pogo effect. In other words, it's complicated to get all the settings working together for the best overall result. After owning a highly adjustable suspension on a bike years ago, I've never felt the need to buy another. If I was racing then yes, having all the adjustments available can make a difference.
Before you give up on those shocks, see if you can get some help with those damping settings. Once you get them set right, it shouldn't be necessary to constantly screw with them.
JMHO - Jerry