the trend with the pros is to get the smallest frame possible with the seatpost and stem to make it work. according to Leonard Zinn the Discovery team (or was it USPS) took delivery of their equipment one year but the stem supplier only had 14 cm stems. so everyone used them at the training camp and after doing loads of miles, the riders were reluctant to go to their "correct" sizes. in another example, he said that BH once provided all their riders with the same size frame. Heras was on the team as well as VandeVelde (extreme ranges of height). stems and posts were sourced to make up these size discrepecies.
with a 56.5 tt and 9 stem, if you went to a 53 tt, you'd need a 12.5 stem. this would be good if this is the position you want to have.
*however* if you're thinking that it might change then it may not be a good thing. how aggressive a position do you want?. if you're looking for a more aggressive position, lower and longer, then you may want to do some extensive measurements to see what's possible.
For example, if you go to a 53 cm frame, the head tube might be 3 cm shorter. this means your bars are 3 cm shorter for the same stem. is this desirable? I went to a frame *specifically because* the head tube was 3 cm shorter - till then I had a 13 cm Ritchey adjustable stem pointed down. now I have a flat (73 deg) 13 cm Ritchey stem.
try exploring the limits of possible positions. for example, are you comfortable with your hands resting on top of the hoods? this is a position a bit longer than say the drops. would you want the brake lever hoods where your drops are now? put a bar (even a ruler would do) across the drops of the bars and hold it and pretend that it's the tops of the bar. do you think that's manageable or desireable? try holding your brake lever (i.e. the ergo or sti lever) as if it were the drops. this would simulate increasing stem length by 3 cm or so.
best yet, you might be able to borrow an adjustable stem (or sit on a fit bike or similar). try riding the trainer with the stem way out, way low, etc.
once you start looking at the range of possibilities, I think you'll find the position (or at least the general range of position) that you're looking for.
good luck
cdr