If you look in the Repetier firmware files (communication.h) you'll see Baud Rate settings with comments; note the error rates for different bauds - you can change these (I changed mine from 115200 to 230400 about a year ago and have not had drop-out problems since. Perhaps just good luck along with proper flow-control and cache settings...). Also, with the setting at 230400, I can set s3d to either 115200 or 230400 without dropout/issues so, perhaps it doesn't matter...
You'll need to re-compile and re-flash the firmware into you printer if you want to make the change... but, you know that and how to do it
