Hand crossbows and light crossbows do require significantly more investment to make effective use of. Without the Rapid Reload feat or a similar option (there are low-level spells, magic items, etc.), reloading requires a move action. The rogue class gives proficiency with hand crossbows, otherwise you need Exotic Weapon Proficiency for them, too. Light crossbows are simple weapons, and every player class except druid and monk get proficiency with them.
If you go with Crossbow Sniper while using a hand crossbow, you also need to remember that its range increment is only 30 feet, so anything in your extended Sneak Attack range imposes a -2 penalty on your attack roll (or -4 at exactly 60 feet). If you're doing this often enough, you might as well use a light crossbow with its 80 foot range increment, and can be fired one-handed for only a -2 attack roll penalty if needed. Not game breaking, but significant enough to be worth remembering.
You still need two hands to reload a crossbow, even if you're firing it one-handed, so with Rapid Reload you're not even really freeing up a hand for other things. There are some options to enable one-handed shooting and reloading, although I'm not familiar with them offhand.
