The BIG difference is that you'll know about it, because the warrant will go to you. Not only will you know about it, but you can control the timeframe in which you respond as well as explore legal challenges and remedies. You will be in control of how things play out.

The IRS isn't going to break into your mail server.

People should really, really be running their own mail servers, and I suspect should be providing their own dialtone as well. The latter is certainly much more complicated and technical, but that level of control is a very nice thing to have.