Thanks all for your input.
I ended up picking up a 2006 CAAD8 frame, and I'm building it up with SRAM Red, ultegra, and 105 components. I think it'll be a great compromise for me. Should be stiff enough for my needs, will come in at ~17.5 lbs with somewhat racey training wheels (williams WS 30), and should be pretty good kit. my total cost pending the sale of some take-off components will be <$1000