I have red dots on both of my crossbows (as well as all my hunting rifles).
I don't like magnification and, at crossbow ranges, its hardly necessary.
The crossbow scopes sold by Excalibur have you making adjustments to your point of hold, depending on the range of the target. The last thing I want to have to do (or FEEL I have to do) when confronting a game animal is precisely estimate a range and calculate hold over (or under) based on that range.
With my red dots I establish a point-blank range, and make myself adept at determining if an animal is within that range. I then just point and shoot. No nerves to mess up my "calculations".