You may want to rethink that extending range part. Some vertical bows do that and more now. With practice and patience you can do that with a crossbow...some of the time. I can hit my 50 yard target with a crossbow all day long when practicing; it's quite a different story when it comes to real live game. It tends to move. Crossbows are much louder than vertical bows and there isn't much that can be done to make them a whole lot quieter. So unless the game is unaware and relaxed a 50 yard shot is unethical IMO.
They are fun and perfectly suited for hunting where gun noise is an issue, I just think that 50 yards is an outside limit rather than a given.
By the way, don't be surprised if your local shop is not too informed about crossbows. I actually got the local one to order it's first for me. Since they don't use them, even now they don't know all that much about servicing them or what works. I live in Detroit Lakes, Chuck and would be very happy to talk with you about the subject. Currently shoot two recurves and a compount crossbows, make my own arrows and strings as well as bow press, string stretcher, etc. Just send me a PM and I' give you my phoine no. And/or you can talk to Dave at Wyvern Creations (603-659-05750 he is very knowledgeable and great to deal with.