Standardizing and simplifying your network will work on all devices. I suggest you to invest the time you are using to force N900 into sth it can't do to configuring your network and rather post some questions about that, they're answerable

About the Maemo's networks handling. Yes, its poor. But try to take a look at the output of:

gconftool -R /system/osso/connectivity/IAP

ICD on Maemo uses IAP IDs to identify certain connections, maybe if you re-add your networks so that the one with a higher priority gets lower id (id is random), it will work. Or maybe higher id. Or there is another parameter...

You can get a little bit more detailed info at: http://wiki.maemo.org/Phone_control#...ved_connection