Hi and welcome to the forum. The SRG is an outstanding cooker because it does smoking, roasting and grilling so well where the BEESR does a great job at roasting and smoking, grilling not as good.
Now with GrillGrates it will grill but the SRG does a better job and larger cooking surface. Same with the cooking chamber it's larger and will hold a larger turkey or roast
If cooking for 3 + folks most of the time get the SRG, you will need it's larger size. But the BEESR is an ideal camping cooking and perfect for 2 to 3 people