Here's why I don't use sbm. My comments are based on a limited, perhaps naive knowledge of sbm. Feel free to correct me.
The sbm is by default limited to 8 buttons. It's possible to go beyond this with some know how, but then you're rather negating any benefit of the sbm. Google this problem and most solutions will suggest build your own rather than trying to walk on water.
The sbm is limited in structure. Each button has to be the same (size, vertical position). I can't, for instance, have two columns of buttons afaik. All the labels have to be the same font.
Due to the enforced structure I cannot create custom buttons e.g. a button used in combination with a date selector
I can't make some buttons invisible e.g. based on the user's security
Every switchboard has to follow the same layout. Any style change on one will affect all others. So I can't have my customer switchboard as a different design to my product switchboard e.g. graphics for specifc switchboards.
I cannot create a button to directly open a form in datasheet view (sbm is set to single). I can get round this be writing an intermediary function. But the point is, why bother when this is a trivial exercise if I'd rolled my own.
Interestingly the Northwind Traders sample database does not use sbm. The main switchboard in Northwind is a good example why.
Personally I think the structure imposed by sbm is of the 80's. Interface design has evolved since then.
Chris