Having used both the 200 & 500, both have pros and cons.

200 + very quick sat lock, very simple to use, can re-charge on the go with with standard USB cable, clear when you have started/stopped (when using the buttons), long battery life.

200 - Less sampling than the 500, when stationary it will always show a very slight movement (speed), no clock

500 + better tracking/accuracy than the 200, (samples more) ability to use Cadence/HRM, when stationary, it registers as no movement (speed), long battery life. has a clock

500 - Longer time to get a sat lock, this can be frustratingly long, not as clear as the 200 when starts/stops (when physically using the button to pause the device) can't charge on the go without special cables

Both devices have the same build quality, the 200 is in desperate need of a replacement/update, it's been out a long, long time, and other manufactures (like Lezyne) are now doing the similar but with more functionality/bluetooth, given the 510 is out, would take this as the 500's successor, so it already has a replacement.

Having both, probably use the 200 for 90% of my riding, as it is overall easier/quicker to use than the 500.