Hey yhayamura,
I was almost in the same situation a few weeks ago, and I can share my experience, maybe it will help you
Just a few details: I applied on my PGWP on May 12th, with my SP expiring on May 30th. I was planning on staying in Canada with my implied status until the reception of my PGWP. My mother was supposed to visit me for my graduation, and we had planned a 10 days trip.
Unfortunately, an event made that I had to go back to my country on June 6th. I came back in Canada with my mom on June 12th, because I didn't want to miss the graduation and cancel our trip.
Anyway, when we arrived at Montréal airport, things got a bit complicated. The agent at the immigration desk started to ask me a few questions (if I had ever been to Canada, what was the purpose of my stay, etc.). I could not say that I was coming as a worker or a student, because I had basically no document to prove it: I didn't have my PGWP with me (still don't have it), my SP was expired. That's why I said that I was coming as a tourist, which was true because at that time, I was with my mom and we were supposed to go on our trip. Then I was sent to an immigration office where I got questioned for 20 min. The immigration agent was kind of rude, asked me a lot of questions (including the places we were planning on going with my mom, the name of the hotels, what I was planning to do after the trip, etc.). I answered honestly, without saying too much, because I didn't want to say that I was not a simple "tourist", since I was also waiting for a work permit. He took my passport, typed my name on his computer and saw that I had been studying in Canada for two years, and also that I applied for my PGWP. I don't know if it worked in my favor or not, but he finally let me go.
So, if you want my advice, if you can stay here, stay. Re-enter is not easy, I thought that the agents were really suspicious and it wasn't my best experience, even though they let me in. Also, I may be wrong but if you leave Canada, you loose your implied status and as a consequence, the right to work here. Since this is what I've done, I am officially a tourist and I cannot work/study. I knew all that before I went back to my country in June, but I didn't have a choice and I also thought that CIC would be faster to process the PGWP applications... I've been back in Canada for two months now, and being there without working and bills/rent to pay can be a little bit complicated.
Sorry for the long post, hope this could help you!