Thank you for all your replies, this gives me much needed informtion. Thanks especially to Dynaryder for the link to Sheldon's gear calculator, that should give me a clear idea how a double crank will compare to my current triple crank set. I also agree that I've never had a problem with tuning a triple crank. My biggest concern is the 10 sped cog bumping up the costs of replacement chains and cogs well over my current 7 speed cogset. Thank you all again for your time & sharing your knowledge.
I don't know if this was mentioned previously but I don't recall seeing it, 7 speed chains are also more durable than 10 speed chains. Yet another fact to consider.