so ...
here are my personal conclusions based on what I've seen so far:
regardless of using a LOCAL module or using a REMOTE module, it seems obvious that if you want to get the data in as quickly as possible, then you MUST set the RTS to a LOW number – so that the module will "measure the signal" rapidly/fast/often enough to meet your speed requirements ...
if you're dealing with a REMOTE module, then you MUST set the RPI to a LOW number so that the module will "transmit" the data to the processor rapidly/fast/often enough to meet your speed requirements ...
if you're dealing with a LOCAL module, you can set the RPI to a HIGH number without degrading the speed ...
the inevitable trade-off to this "make-it-go-faster" approach is that the data might be more susceptible to picking up more "noise" as you increase the "measuring" rate with a faster RTS setting ... I'd recommend making it "fast enough" to meet the requirements of the system – but putting the "pedal-to-the-metal" is probably not always a good idea ...