I have owned many First lite pieces over the years. Their sizing has definitely been one of their only negatives. I live in BC and have shipped many items back to exchange for a new size. That being said any items in the last few years have fit very close to size. If you are ordering a long standing piece that has not been refreshed (called 2.0) just be cautious and know it will most likely fit big.
I would say you would be a large in their clothes.
I have many items but my favourites are: the wick hoody, fuse hoody, tag cuff beanie, catalyst pants for late season and the uncompaghre puffy (old version).
Overall great clothes, great company and the customer service has always been very easy to work with on exchanges. So other than it costing a little bit to ship the package back. I wouldn't be too concerned if you had to exchange something.