Thanks, everyone, for your sharing experience and opinions. It has to be remembered that any question on a forum like this will be answered with a variety of responses, the vast majority of which are valid, well-thought-out opinions. In a case like this, there is no consensus, and no one should expect one. It is, quite frankly, much like the chorus of voices already chirping in my head about this issue. I've had both sides of my internal debate reinforced, so I can just go ahead with the knowledge that there is no right answer and simply look for the best deal - ALL things considered - when I'm ready to lay the money down. Cheers!

If you already own a bike you can surely think of several things that need tweaking, fixing, or tuning. I have some shifting issues between the 7th and 18th cogs when in the large chainring. But I am aware of them, and of how to deal with them so they do not impact my ride.

A used bike will have someone else's list of grievances. If you are handy with a wrench this is ok. If not, buy new.

I guess that 18-speed technology is yet to be perfected.

I think that you are asking the wrong question.

How you fit on the bicycle affects your comfort efficiency and performance every single minute that you are riding. Nothing else, like frame material or component group, can even come close in terms of importance.

I would never pay $1,200.00 for a ten year old bike.
There's just too many good deals out there on new bikes and \ or newer used bikes.

X2 This is solid advise!

I dunno where you live, but if it's near a major metro area (?), I'd suggest going buy a "Bicycle Rescue" co-op or non-profit. They get most of their stock from police departments and other legit municipal donations. Many non-profits can't really handle bikes per se, so they pass them along. Bike Rescues often are staffed with very knowledgeable bike mechanics who donate their time. Most have upwards of a 100 bikes to choose from. They love fitting folks and helping them get into what they want. The goal is assemble a keeper so it won't come through the system again ...

Go look and see if you can find something that really sparks your interest. Often they have bins full of good used parts. A solid chassis will start at $100 or so and they can build it out from there. There are some real high end bikes that get stolen and never claimed (as in from out of town/state) so they are out there. The Police have cleared them of prior ownership. The original owner took the insurance money and bought up. So you can get some nice stuff, and they will make sure it fits you. Take a look ...

We have a place like that in Boise. Awesome people with a passion like us. I highly recommend this route.

New is always better as no hidden agendas like fractured frame or fork and everything is lubed including cables.

With used bikes you can reach for better components, if you know what to look for.