Should be OK. Depends on how big your DHCP scope is. I configured DHCP on my measly 1720 routers in the past, with only 32MB DRAM, and they coped pretty well. Mind you that I only had /27 subnets on those.
The problem with enabling DHCP on your Cisco devices is that, as far as I'm aware, you can centrally manage them. Unlike using DHCP s/w on servers (e.g. Microsoft DHCP), that allows you to centrally manage all of your DHCP servers. If you're not worried about this manageability issue, and if your LAN ain't that big, then why not?
