I have both the BR2 and the SIG. Sig kicks the BR2s but when it comes to a ballistic solution. I haven't used my BR2 in a while, but if I recall correctly, you input wind in 5 mph increments; SIG is 1 mph and you enter using clock directions. SIG accounts for spin drift and aerodynamic jump; BR2 does not. BR2 is pure black, which if left in the sun heats up and shows temps higher than ambient (SIG has some black).
SIG does a terrible job in fog or snow; not sure how the BR2 does. SIG will range out far, but yesterday in bright sunlight I had to range several times to get a reading at 1180. Two other issues with the SIG: you can load unlimited ballistic profiles in your iPhone, but can only load four into the rangefinder. MAKE SURE you have the right profile. Not an issue when hunting, but I always shoot multiple rifles; in CO last month I missed my 24x24 gong completely - I was like ***?? Then I saw I had the wrong profile synched to my rangefinder. The other issue with the SIG that is sometimes frustrating is inputting your wind via iPhone and then synching. It sometimes doesn't sync, but you will know because your wind holdoff will be zero. You can input wind manually as well, and it is pretty fast unless you need to go down in wind speed from your previous - they you need to go all the way up to 40 mph before it goes back to zero on the toggle switch. Two switches would be infinitely better.
SIG is smaller than the BR2.
Like I said, I have both but the SIG is what I use now. When the Trijicon Ventus comes out, I will try that one, but it won't come cheap.