Hi Jordan,
Not the CA44. For your weight the Carbon Art 40 would be good for flat water speed conditions. I am 75kg and find the CA44 too scary loose for me. It suits heavier guys better from 80-85kg up.
I really like the Starboard IS50 when conditions are choppy (for a flat water speed course

). It rides very smooth and safe in radical conditions. Maybe not the ultimate edge in ultimate speed conditions that the CA40 has, but there is not much in it and the confidence it gives me to push to the limit can often more than make up the difference. From what I have seen of the newer IS speed boards, they also look like they ride very safe and smooth over chop. Go for the smallest one though if you look in this direction. In comparison, the small CA duo are a lot looser and more high strung. For the CA40, that puts me a bit more on the edge, a lot more flighty, but just in control and in ideal conditions give a slight edge in top speeds. The CA44 for me is over the edge and feels like it is about to take off and fly at any moment. Not conducive to building confidence.
There are probably some very good deals around on IS50's and for your weight you will find it carries you very well in marginal speed conditions (18-20 knots) as well as feeling good right up to full on manic conditions (30-35+ knots). The IS 50 will work better in most conditions with a more raked fin as well, and if you are under 6ft you will benefit from a closer, more rearward stance on speed runs. see Toms pictures here:
http://www.mtbest.net/isonic50.html My board it set up the same for Starboard tack speed runs.
You might consider this board as well:
www.seabreeze.com.au/Classifieds/Windsurfing/Boards/~0d_l/2006-Starboard-Pro-Kids-Sonic-Speed-Board-212-cm-50-litres.aspxHope this helps