In most cases all you need to do is press the ILF bushing out of the limbs, and press in a set of GameMaster/Dorado bushings. I some rare cases you may have to use a sander to remove some stock from the limb butts, and in even more rare cases you may have to use a round file to take a little stock out of the limb bolt slot. It's very easy to adapt any ILF limb to a Dorado riser.
Negative performance? I can't think of any. In most cases you can enhance the performance over the stock limbs that come with the bow.