If you're riding a 52cm~54cm and climb well enough how heavy can you be? Also, if you are going with a compact to spin more on steep pitches stiffness will be less a factor.

Honestly, I don't think you will notice much in the way of stiffness from any frame you buy based on these facts (assumptions). I would suggest you move stiffness down the list and look more at geometry and ride quality (of course, aesthetics matter. too). This might open up other options to you.

For the record how much do you weigh?