For the ‘pi and more 9‘ in Trier on 11 june 2016, I had the chance to run a workshop on how to use scratch with gpioserver and as an alternative to use scratch with scratchClient.
Basis setup was to control three LED with a button.

The introduction is available as a pdf-document.
The tutorials are available here: tutorial (de), tutorial (en).

Working with gpioserver was found to be unstable. Quite a few  attendants had problems to get a connection to the hardware. It simply did not work, or they got popups in scratch that connection to pigpiod could not be established. It was needed to stop scratch and restart to get it running. A reboot of the computer was needed to cure the problems where scratch complained about missing pigpio.
In the scratch startup shell script, there is a check for pigpiod, and when not running this code is started. Obviously this does not work stable.

The differences between using gpioserver and scratchClient have been clearly visible in this workshop:
gpioserver does not complain about misspelled commands, and there is no monitoring capability for this tool. So when something is wrong, it is difficult to find the problem.
scratchClient needs an additional tool to be started, and multiple startups have been a problem. But the monitoring features with the web tool  localhost:8080 have been acknowledged as valuable in training environments.