It depends on what you need to do with your switch. There are a lot of things that the Enhanced Image (EMI) has over the Standard image (SMI) . The enhanced image will give you the ability to use this as a true layer 3 switch. It will permit you to use EIGRP, OSPF, RIP and other protocols that you would normally only see on a router.
Along with that applying ACL's to ports so that the switch can take care of security before it ever reaches the router freeing up cpu cycles that would be used for other things on your gateway router.