I had a specialized road bike with Alex EXA330's on them. Those wheels blew chunks. Not stiff at all (when I jumped out of the saddle I could feel the wheel flex and rub the brake pads on either side), they came out of true quite often and they had a huge welding seam that made them heavier in a spot. I have never read anything good about Alex wheels written by anyone who has ridden on anything else.

I have Ksyrium SLs on my tri bike. They are great wheels but not aero. I have them on my tri bike because my Cannondale came with Ksyrium Elites and my LBS threw in an upgrade to SLs for free - so I was like "cool, thanks." I don't know what your budget is, but it would probably make the most sense to keep the Alex wheels for training or get some other wheels for training and then get a set of zipps or something for tris. I had my LBS build me a set of Mavic Open Pros with ultegra hubs and 32 spokes for training on my road bike. They are only 1800g (not bad for training wheels) and are bombproof. They are 3x spoke placement so they are super comfy. A thing to consider - I sold my Alex wheels on ebay and I think I got $200 or so for them even after I ridden on them for 1800 miles. Maybe if you don't ride on your Alex wheels at all you can sell them on ebay for more than that and help fund another set of wheels. I have read good reviews of the Neuvation wheels that are sold online.