Yeah home replacements work well, once they are full integrated for the 2.0 moto droid, there shouldn't be much issues, as some come with 8 some with 5, 3... Folders do help for the most part. I think i'd be more then happy with 5... 11 seems like it's just way to many (not a bad thing though). But hell i mean if it has 11 and i don't use them, i don't mind them being there if ever need.
There's a number of apps that work on previous versions of Android that need to be fixed by the developers before they will work on Android 2.0 which is on our Droids. ChompSMS is one I'm waiting for and I'm guessing OpenHome must be in the same boat.
I think the # of home screens was given as 3 for a reason. They want to gage performance. THe more home screen available and people have stuff on there, the transition between them will begin to lag. I think they will release an update with more home screen, but slowly adding, rather going straight to 11 like Apple iPhone
Not sure if the apple GS has "widgets" on their screens, I only recall icons and my wife's only has little icons that don't do things like updated facebook posts, etc. However, on the android because it does allow real-time updates to the widgets on the screens, I can see where more of them might allow a user to put a lot more interactive widgets on the home screens and bog things down. Just a thought.. not entirely sure on this yet...
Droid has 3 screens as opposed to the Eris and Hero because the Eris and Hero are running custom, modified versions of Android 1.5 aka Cupcake. The Droid is a Google Experience phone which means that the operating system is in a state sort of "as Google intended" which is three screens.
Edit: Also, widgets are the biggest resource hogs of all on Android. Loading all five of a Hero's screens up with widgets makes it pretty laggy. Don't despair.