LOL, as you can see there are a number of things to determine what resolution you want to work in. Sometimes I just like to make sure I'm covered and that's why I use 300ppi. If I can eat anything with a spoon I don't really need to carry anything else with me into the woods right? Remember you can always go down but you can't go back up. Say you made an awesome battlemap and folks just loved it. Someone comes along and wants to print out a high quality mat of if and wants it in 300ppi for the ultimate print. Well, if you made it with less you are hosed. Of course, if you are use a vector based software I don't think any of this matters, you can scale up and down like a mamby jamby.

The only disadvantage with going at a higher ppi is that it's going to eat up more drive space and memory. If you don't have an awesome rig you will feel it. I can't tell you how many times I've clicked to select something, missed it by a few pixels and had to wait for 15 seconds or so while the stupid thing found everything I inadvertently selected. Grrrr.

Note: I say all this because these are the things I have picked up being here. If I am in error don't worry about my being offended, just show me where I'm mistaken that way I learn something new.