I am using a BAUDrate of 115200 since I cannot make a connection to my printer with the advised 250000 rate. Are there any downsides or limits I reach earlier given by the lower BAUDrate?
Baud rate is the rate at which information is transferred in a communication channel, given as a number of bits per second (bps). So a baud rate of 250000 is capable of transferring a maximum of 250000 bits per second (31250 bytes/s). When working with serial ports, both ends of the communication line will have to "talk" with the same speed - the same baud rate - to understand each other.
So when using a baud rate of 11520 you will theoretically be limited to transfer data with about half the speed of 25000. If you are transferring large amounts of data, this might be a limiting factor for your application, but if you are not pushing the limits of the your serial port, it probably will not matter at all.