Bachand - Though I cannot make the decision for you, there are some things to consider:
What do you plan to do and where do you plan to stay - If in a L/T, you might wish you had the heavier bag, especially if it gets cold and damp or windy. A tent will keep you warmer by slowing the escape of warm air.
What rating is your fleece sleeping bag? I have a very light down bag (45d) that I really like - especially the weight savings, but wouldn't take out right now - It allows no margin for error.
I look at it in this fashion - Am I prepared for the worst possible weather and the most reasonable worst case scenario - Say a freak cold front follows a heavy rainstorm and sinks in the area - will you be prepared for a cold evening and night
My most reasonable worst case scenario might be either slipping on cordoruy or rocks and fallng into a stream or marshy area getting soaked or walking all day in a deluge (or having to walk throught soaked trails that have not been brushed out in a year or two as has been the case there) and having everything cold and damp at the end of the day.
Will I wish I had the 10d bag - absolutely. Will it be worth carrying he extra pound or 2 - absolutely.
I consider my sleeping bag the last piece of protection I have and my final shelter, if all goes wrong.
FWIW, I can remember one time going through the West Canada Lakes back in '95 and it got so cold one night - it down into the 30's, (this was June 23 or 24) that the next morning, when I dunked my pot in South lake to get water, the water was warmer than the air. I skedaddled back to my tent and into my sleeping bag while my coffee water boiled - I drank my coffee in bed that morning
Good luck with your decsion
Rick