I second SadieKate's recommendation - check the gear inches, and be very sure of your decision. I'd do the gear inch calculation on both bikes and compare the gears that you usually use on your existing bike with those available on the proposed configuration.
There is absolutely no reason that a bike with a triple shouldn't shift smoothly and quietly. I have a triple on all of my bikes - both road and touring - and they all shift perfectly and quietly. And a work friend bought a very high end custom road frame recently. He originally was going to get a double, but after thinking about it and realizing that he would like to take the bike the Europe at some point and ride in the (big and steep) mountains, he put a triple on the bike. (And before your LBS says something about a big "guy's" frame for that example, the guy I am talking about is small - maybe a little bit taller than me - I'm 5'5" - and has a small bike frame.)
I'd recommend not going with the double if you have any concerns about the range of gearing.
--- Denise



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