Yes, as indicated by others, the limitation is not in the amount of devices.
There are several considerations:
-How much ambient network traffic do you want
-Where is the Dude server on your network
-Are you using agents
-The effect of polling intervals on creating network bottlenecks
-Power of your server(s) or network
I successfully pushed the limit (just for fun in the middle of the night) of a Dude server monitoring hundreds of devices. I set the default polling interval to an insane minimum level, something like 1 or 2 seconds as the default for the entire network. I also set any other parameter to as low as it could go. At that point, I almost lost touch with the server! I managed to throw down about 50Mbps of SNMP/ICMP traffic, and a very substantially powered server got to about 50% utilization. (2x3GHz Xeons with Gig-E). Many other network problems began to surface of course. Do not attempt this unless you are prepared to deal with the fallout!
So the moral of the story is that the Dude is a highly scalable platform, largely due to the implementation of Dude agents. (It is also a good example of scalability) If certain bottlenecks are reached, scale the installation to remove the bottlenecks. If that doesnt work, I would like to know where that network is, and what its doing