I was doing more testing with different cables and found there was something other than cables slowing me down. I was not shooting Raw and Native as I thought.
There is a disconnect between the Indi Control Panel -Stars Image Settings(Screen that pops open on Connect) and the Ekos -KStars CCD and Filter wheel settings window. In Indi Control Panel Image Settings Tab Capture was set to RAW and Transfer Format is set to Native. I didn't notice this does not affect the capture format in the CCD & Filter wheel tab. Or Maybe they have different meanings that I do not understand. I am still on the left side of the learning curve.
My transfer speeds, when set to native in the correct tab, are similar to yours. 6 seconds or 7 depending on if I have the save to SD option. I have pulled the fits speeds down to about 30 seconds by adjusting different options. I am still "tweaking" the settings to reduce the fits transfers. For comparison, My image files are 31Mb in cr2 format and 48mb in fits.
I have been using the 16Gb SanDisk Ultra SDHC. I found a way to benchmark them in the rPi using this website listed below. it seems the SD bus is limited to around 21MBps. it mentions some overclocking options that I am going to explore with a new SanDisk Extream SDXC I just picked up.