The gain you'll get in FPS probably will be pretty small. If I remember correct, which means I could be way off, I thought it was something like 1-2 fps gain for every 5 lbs increase in DW? If that's the case, then increasing your DW won't really give you much of an advantage and really just cause you to have to do some slight retuning. Remember as well that your shoulders are not going to be used to this increased weight which will reduce your stability when holding, do you really want that problem on stand? Also, consider your arrows, if you're on the lower end of the spine spectrum, increasing your DW could cause some spine issues as well. From what it sounds like your bow shoots just fine the way it is - why mess with it during the season?