Will a I2C switch boost the overall bitrate?
It's hard to say. If you are running in to rise time issues due to the capacitance on the line, then segmenting the bus will alleviate this issue. However, you will pay a penalty in terms of the switch configuration overhead. You'll have to do a usable bandwidth calculation for both cases and see which one is better - raw bit rate for one, bit rate times efficiency for the other.