i've always had a personal thing against the shape and design of the cannons (its just an imo tho) they seem okay when your do handheld stuff or on the shoulder but as soon as i mount it on a tripod or on a stready cam it seems un balanced.
i use a couple of sony PD170's myself in the studio and have completed projects for the various blue chip companies using them. my advice is find a friendly retailer with a studio on the premises and go for a couple of hours and have a good play with both cameras. also have a chat with the retailers experts too explaining what you want to do, where your planning to use the camera etc...
good luck and welcome to the world of prosumer video!
Awai.