If you intend to run DSLstats on it I would be interested to know how you get on.
Since I installed the latest version of DSLstats and enabled the webserver, the RPi Zero W CPU is running at 100% for a significant proportion of the time, so response can be a bit sluggish. Ideally I should like to put the data store on a USB pen drive, but I'm not convinced the RPi could cope.
The 3B+ sounds like an ideal replacement if the router USB can handle the extra current load, but it's a significant investment (relative to a Zero W) and I need to save up some pennies first!
Finally received the RPi 3B+ this morning, set up on Raspbian Stretch running DSLStats and the kitz webserver interface on Chromium browser.
As would be expected, by direct comparison to the RPi 3B, everything loads and runs faster with the CPU activity recovering in a shorter time after sampling activity.
For reference, carried out comparative power consumption tests with the RPi 3B using this:
https://www.amazon.co.uk/Muker-J7-MultiMeter-Compatible-QC2-0-QC3-0/dp/B01D9IFJGO?th=1with suitable adaptors running from a 2 amp, plug top PSU.
Ran both RPi's headless (to avoid mouse & KB loading) with Wi-Fi connection to router.
Ran RealVNC Terminal, DSLStats and the kitz webserver interface to Chromium browser for the tests.
Results:
RPi 3B, program idle, average current, approx. 220 ma.
RPi 3B, program sampling, peak current, approx. 330 ma.
RPi 3B+, program idle, average current, approx. 370 ma.
RPi 3B+, program sampling, peak current, approx. 460 ma.
Ensured that the USB supply voltage remained at or above 5 V. during the testing.
Obviously, difficult to accurately read a transient current on a digital display, sufficient to say in response to the question by Westie that the RPi 3B+ would be very near the 500 ma. current supply limit when powered from a router USB port and probably best separately powered.