I used the fl2k_test program to check the sample rate I could get through various USB interfaces.

First, through a motherboard USB3.0 connector:

$ fl2k_test -s 162e6
Reporting PPM error measurement every 10 seconds...
Press ^C after a few minutes.
real sample rate: 109697891 current PPM: -322853 cumulative PPM: -322853
real sample rate: 109648409 current PPM: -323158 cumulative PPM: -323012

109 MHz.  Not bad.  Now through a USB 3.0 hub:

$ fl2k_test -s 162e6
WARNING: Failed to set sample rate.
Reporting PPM error measurement every 10 seconds...
Press ^C after a few minutes.

real sample rate: 86140872 current PPM: -468266 cumulative PPM: -468266
real sample rate: 84019530 current PPM: -481361 cumulative PPM: -474994

84 MHz is a little worse, but still not bad.

I seem to get "WARNING: Failed to set sample rate" randomly.

Now, through a USB 2.0 port:

$ fl2k_test -s 162e6
Reporting PPM error measurement every 10 seconds...
Press ^C after a few minutes.
real sample rate: 14560550 current PPM: -910120 cumulative PPM: -910120
real sample rate: 14561029 current PPM: -910117 cumulative PPM: -910119

14 MHz.  Still good enough for the MW generator.  I could even bump the sampling rate up from the current 8192 kHz.

I still have to try this on a Raspberry Pi.