Since the egg can do it, why not try 275°? Should be around 4 hours. Try Disco's trick of taking them to 180° then resting them til they cool to 150°.
Not foiling changes the timing a good bit and also makes for firmer meat. If you're a fan of "fall off the bone" ribs, you may wanna keep on foiling. I like my ribs to be the texture of perfectly cooked pork loin. Did a fair bit of experimentation and settled on 275°, smoke til I got the color I like, foil for 30-40 minutes until they pass the bend test, then back in unfoiled for 15-20 minutes just to dry the surface and set the glaze or sauce if I'm using it. It stil isn't as consistent as I'd like, which is why I like Disco's idea of target temps.