If you leave the protection ciruit installed, then it won't be any different than what would happen in your camera. The circuit will protect the cells from being discharged to a detrimental level.
About a month ago, I made a Li-Ion 3.7v 3700mah pack for my SL Stinger, using two 18650 cells in parallel. There was no protection circuit installed; I thought I could manage it on my own. Unfortunately, I did my first discharge test at about 2 or 3 in the morning and dozed off. (Brilliant, right?) When I woke up, the pack was at .57 volts. I thought it was a goner. But after letting rest it for an hour or so and then applying a light (for 3700mah) 100ma constant current charge, I was able to get the pack above 3.0 volts. I then charged it normally. I have done a few more discharge tests since, and the pack seems to be fine, although I certainly don't know how affected it is for the long term. Heck, it could blow up the next time I use it, for all I know.
