I didn't have a problem staying in HK for a year after I resigned. My employment visa was valid for 1 year after I stopped working and I came in and out of the country without any issues whatsoever. Inland Revenue (not Immigration per se) was informed as my ex-employer completed an IR56 form. When my employment visa expired, I then entered the country on a 180 day tourist visa! During this time I found a new job ;-)