Yes, my driver supports all the way back to v8.1.0, so only reports on the Web UI through the older metrics system, showing "Load" instead of the new "Overload". Where my stats collection makes it possible, I try to generate the same diagnostics tags as the IA driver, but queue duration doesn't behave the same.
I also generate stats for non-subscription reads and all writes, on a one-minute basis.
For actualSamplingInterval, I report the time from start of a poll cycle until the last response is received. My driver does not spread polling out across the entire interval. The old "Load" UI handles the stats I give it in some opaque way that I don't understand. I recommend dividing my actualSamplingInterval by the scheduled interval to obtain a "load" estimate for my driver.
Your driver (IA's) doesn't provide any metric that can be used to determine any free bandwidth.