Voiding the warrante probably isn't that big of deal for most folks. It's a pretty inexpensive rifle anyways, and simple too. Should something go wrong, I'm sure a gunsmith could fix it, or you can just buy a new one.
I plan on altering the hammer too, as soon as it gets back from the factory. I'm going to take off a little bit of hight from the hammer and then add a hammer spur.