Many brands of pellets are overpriced blends with a relatively small amount of flavor wood. Either go cheap (Pit Boss brand) or go with Lumberjack (100% flavor wood). Traeger, Louisiana Grills, etc are a rip.
Wait until spring when all of the new models are out. None of the cookers you're looking at are going to perform much different than your Daniel Boone. Pit Boss, Weber and others are coming out with new designs that would be a bigger upgrade.
Sounds like the flame went out. Could be low ambient temp or too much ash in the firepot. Clean your cooker out and try again. If it's really cold you may need to run a lower p setting to keep it burning.
The bottom may hang a bit close to the coals to run without a water pan. And I would keep water in it or the drippings may burn up and put a layer of burnt grease on your ribs, unless you're running really low and slow.
I have the Dynaglo Signature Series offset too. Runs great as a stick burner. The grates are only 16“ so laying ribs down flat is tight but if you get a set of hooks it's perfect for hanging full racks.
Some of the Pitboss grills have a sliding heat deflector to allow for direct heat grilling. It's not completely open over the firepot however. There are slots in the heat deflector to allow some flame and heat to get through.
P setting regulates the time between augur activation. If it is running below the temp you set it to, lower the p setting. If it is running hot, raise the p setting. That said, the cooler it runs the more smoke you'll get and smoke production drops off with higher temps. You can play with it by...
Hours. Bacteria does not travel through whole muscle tissue well at all. Ground meat is what's risky. The smoke (and the rub) also kills surface bacteria. Just rinse the meat and it can go a long time. Bacteria growth slows and eventually stops as you get above 125F internal temperature. By 140F...