Is routersim good for testing router config in the real world?

I have a simple network 4 2621's for various uses and a PIX firewall at the gates. I have in the past just kept a couple extra routers around so I could test configs/commands before pulling the trigger. I currently only have one spare and need to make a change on each side of a T1. I just want to make sure I've got my commands down before doing it, because it's a 30 minute drive to each side and I have no help. I was looking around and it looks like for 250, this routersim software will allow me to program 2 2621's and test router across them. Is that correct or is there a better software for the roughly the same amount of cash. It's the company money, but I would feel guilty turning in $1000 bill to save a few miles. Thanks for your help.