Thanks for the info guys, you've been very helpful. Good to know that the Paul Chen/Hanwei blades are well thought of. I liked the look of them myself in the various online stores I've found.
Just in case anyone comes looking for more info later on, I have dug up some purported criteria for choosing the right sword length etc. here:
http://sunflower.singnet.com.sg/~limttk/ysword.htm
Length: Hold the sword in the starting position, i.e. behind the straightened arm, blade vertical. The point of the sword should be around the level of your ear lobe.
Springiness and weight are apparently a matter mostly of personal taste. Neither too springy or too hard etc etc. I guess as long as it feels natural in the hand while doing the form then it will be OK.
Thanks again guys.