Aptitude is great but I have some unresolved dependencies after dist-upgrade. I wouldn't dump synaptic just yet If I were you.
Aptitude and synaptic both use the same underlying APT system in much the same way, so it is rare that one will work where the other wouldn't.
Try running "aptitude update" again when you encounter problems. The armel repositories often lag behind the more common architectures so sometimes we have to wait...