Why would it be any different for IT to work at home than anyone else? When I worked for a big bank, whoever was on call in IT helped you from home. If you had a problem, you needed help right then, not "when he can get there". As long as you have the security in place to access the systems, I don't know why it would have to be done from the bank.
I take work home all the time with my PC. There is always of course the risk that the laptop could get stolen, but we have additional security on our laptops that won't even allow you to do anything until you sign into the laptop itself. I believe that if you have the appropriate security in place, it should be a non-issue.