Well, i see only the advantages if choose the Router as a DHCP.
Infact as I stated above, If you use Windows DHCP (or any NONE router DHCP) then your internal network will still receive IPs when the router is down or when it crashes. I think this is a big plus for using Windows DHCP.
However my only concern is about Work load in the Router.
Do you have any idea about each router model capacity of handling DCHP Users.
Not sure, The issue is hardware,IOS and network load specific. I think the best way is to really test it for a while on your network and check the router CPU usage using the show processes cpu and show processes cpu history commands. For the first command, it will show you detailed CPU usage for every process running, check the "DHCPD Receive" process if it's at high CPU usage or not. The second command will give history analysis of overall CPU usage within the recent minute, hour and 72 hours.
Note that these commands output may defer depending on the IOS version you have.