The saliva helps protect the horse's mouth from injury and helps keep it soft. If she likes it, leave her alone in it. If you want ti try something else, you could always get a mullen mouth just like it in sweet iron or copper.
A bit is only as bad as the hands behind it. Whatever that other bit is, it's a curb and curbs are actually classified as severe. It's not that they are particularly nasty bits. It's because they amplify the amount of pressure you use on the reins vs. the mouth at a ratio of 1:3. 1 pound of hand movement on reins = 3 pounds of pressure on the horse's mouth (greater or less depending on the length of the shanks). They're also meant to be ridden with one hand, so the people you plan to be putting on your horse should be considered. If you try to use 2 hands on a bit like that, that is when it's going to really start bothering your horse. Curbs also come in different severities. The mildest are the completely fixed grazing shank with a low port.
If everybody's accostomed to riding with 2 hands, then stick with a snaffle.