After reading this particular question, I attempted to implement the following:
protractor test/features/protractor-conf.js --params.test_set=dev_test
as well as
protractor-conf.js:
exports.config = {
// ...
specs: [browser.params.test_set+'/*.feature'],
However, this approach did not work as browser is not defined during the parsing of the conf file.
So, I am left wondering how I could achieve the desired effect of passing a parameter to protractor that determines the specs to be used.