Seriously the database timeout need to be shorter than the switchboard timeout otherwise if this is too close, the database may be successful but the switchboard may timeout milliseconds before receiving the response. I tough that one second shorter is very safe and acceptable up to a timeout of as small than 4-5 seconds. For timeout smaller than that, the value must be less than a second. I am not sure this should really be configurable as this might be error prone but I was expecting comments on my selection of magic numbers... 

You just made me realize that 0.75 and 500 should probably a better magic numbers...