I'm BB.
When originally setup my 145g plan was would always add sand later. After bottom started getting covered in coralline ended up don't mind the look and left as is.
Don't think it's necessary for filtration as I'm zero nitrates and no sand in system but there's always the option of a RDSB or sand in the sump. Adding Ca etc, probably doesn't contribute a whole lot specially with the system pH (why Ca reactors add CO2 to dissolve media) and I ran a 75G for years with a DSB and though added some sand over time, wasn't much overall.
Believe the pro/cons for a sand bed is just aesthetics and what you can keep. Love the idea of the shrimp/gobie pair but without sand I'll live without. Also will admit when I see a nice tank with a clean SB think of adding sand to mine, but the urge passes fairly quickly.
Remember there's no reason you can't add a SSB or a DSB later to a established tank if don't like the BB. Better anyway if the LR was placed direct on the glass rather then on the sand where it could settle.
