I think there are a lot of naysayers because we get a lot of newbies who really dont have a clue about what they want to do or worse yet, dont know how to use tools, so the buy a bike and not parts is good advice for many.

I was in your position a few years back and wanted a big frame for my long legs too. I found an XXL Specialized Allez frame, won the bidding war and went to work. I assembled a great bike from a handful or orders and auctions, and still spent much less than a used one even if I could find a big frame.

Go for it! You might buy a few wrong parts along the way but you'll have fun since you have done your homework.

-SP