I went through a similar process recently. Had a propane grill (Charbroil Tru Infrared) that I used for high temp cooking and an electric smoker (Masterbuilt) for low and slow. I loved the convenience of the electric smoker (automatically maintaining temp), but wasn’t thrilled with the quality of the smoking. I then recently discovered the Masterbuilt Gravity Feed charcoal/wood smoker. Best of both worlds - automatically controls temp via a thermostatically controlled fan and can vary temps from 170–700 degrees for both low and slow and searing. So my plan was to replace both the electric smoker and the propane grill with this new one. Everything I’ve cooked on it so far has turned out amazing - smoked brisket, ribs and pork shoulder, reverse seared tomahawk ribeye and searing burgers and steaks. The one thing I’m not happy with, though, is the warm up time/process and the amount of wood/charcoal it takes to cook anything. Like the OP, most of my searing is for 1 or 2 people, and 1/4 bag of charcoal to cook one burger or steak is a waste.
So... My plan is to keep the Masterbuilt Gravity Feed for smoking or cooking larger quantities. But I’m also going to buy another Charbroil Tru Infrared for cooking just a steak or burger or two (I relocated my other one Charbroil to my cabin). I’m not sure how that Tru Infrared thing works, but what I do know is that it makes a great seared steak or burger. It has a corrugated metal “Tru Infrared Emitter” that sits on top of the burners and below the cast iron cooking grate. It has tiny holes in it that allow heat through, and grease drops on it vs. onto the flame from the burners. This causes smoke from the grease drippings that add flavor similar to what you’d get from charcoal, but in 10+ years of using this grill (I’ve had two them), I’ve never had a single flare up. I simply crank the grill to full blast, let it get up to about 550-600 degrees, crank the flame down to about 3/4 open and throw on my steaks or burgers. Cook 3-5 mins per side depending on thickness. I get a great sear on both sides and the whole process from turning the grill on to preheat to finished product is less than 20 minutes.
My first one was a 3 burner when I was feeding a larger family, but I downsized to a 2 burner model which could easily cook for 1-4 people. Anyway, I’d highly recommend the Charbroil Tru Infrared if you decide to go with propane. They’re not exactly cheap at $250-350, but they are worth it and hold up pretty good over time. First one lasted about 10 years and was still going strong when I moved and left it. Other one is 3 years and still going strong. Only thing I ever replaced in either of them was the igniter in the older one. Was less than $10. I went with the stainless models both times.
Good luck with your research and let us know what you decide!