I did the COG sums for my setup in SBS mode vs missionary position. I found the SBS did result in more counterweight required however it also provides a lot of flexibility in changing scope positions and balancing with the starstuff SBS bar is quite simple as you can move both scopes independently in x and y directions.
What focal lenght are you using? I use the ADM SBS losmandy bar cos it's half the price of others and I shoot under a meter of FL, but if you want to do long FL, 2meters +, I wouldn't use a SBS bar.
