Quote from def:
Steve addressed this in other threads. Globex offers very tight spreads and has certain advantages over FX spot such as the exchange clearing house being counter party to the trade (we only have large international banks as counter party so that isn't as great an issue).
The FX spot however can be traded in the size you prefer which might offer more exact hedging advantages. You can also use spot FX to due currency conversions. I'm not an expert on FX yet so I think it's best to defer your question to those who trade both. Also fyi, Steve is travelling this week and his ability to post is unknown.