Hi - you sent me a PM but I could not reply because your inbox is full... so I will reply here -
I have no personal experience with PGWPs. But just from the information that is available on the website,
http://www.cic.gc.ca/english/study/work-postgrad.asp
... you would qualify for a maximum of 2 years - the PGWP cannot be longer than the length of study. As you need 1 year of skilled work after graduation to qualify for CEC, that should be enough (as long as you can get a skilled job).
BTW - 2 years, 4 semesters - normally I would say are pretty much the same thing. Unless the 2 year program specifies a summer semester (making 3 semesters per year). But without more information (e.g. link to the specific program), I cannot be certain that "16 consecutive months" would meet the CIC definition of 2 academic years.
Also - FYI - the provincial nominee program for Ontario - Opportunities Ontario - has a pilot program right now for those who graduate from an Ontario uni with a master's degree - if either program will result in a master's degree, you may qualify that way as well.
