I've been hunting with crossbows sporadically since tyhe early '80's, and have yet to be successful, so I don't have a lot of info on success to pass along.
I currently use a 150 lb Horton Explorer. This is a compound crossbow, and since I'm a still hunter, I prefer it because it has short limbs that make it easier to move through the thick stuff. I have a red dot sight mounted on it.
Contrary to popular belief, the effective range of a crossbow is similar to that of a vertical bow, and the speeds are a little less than the modern hand-braced varieties.
Crossbows are noisier than vertical bows, so longer shots are less possible due to the increased chances of string jumping.
In Ontario, crossbows have always been allowed during the regular archery season, so we see none of the animosity toward them that I see on many archery sites from the US. Around here, Excalibur crossbows are generally considered to be the cream of the crop. There is an excellent forum at the excalibur web site if yoiu want to bounce questions off more experienced XBow hunters. It's at
www.excaliburcrossbow.com.