I don't know for Open Source project, but I often think about leaving Montreal as it's really hard to find good co-founders and to get investments. Usually, investors have ideas on what they would like to invest and you'd have to forget your project and build theirs. Also, IMO, the french problem isn't a problem since the big majority of the startup world speaks english. For instance, if one person speaks english and 5 speaks french, the conversation will be in english as Quebec people are way better in english than the inverse.