And the winner is... Motorola

After intense reading and searching reviews on the net about GSM phones I found it!
Yes, I already got another one. It's a Motorola V1075 and it seems to fulfill my expectations.. Except for the ugly Vodafone firmware, but I already found some hacks, firmware, etc to change that.
The phone is absolutely superior... it just works :-)

I have some issues with transferring the phonebook from the BenQ to the new phone, I tried exporting the entries as vCard, but it can be done only for one at a time... The phones can't communicate directly because BenQ being Taiwan based was sure that everyone else in the world also uses the Big-5 encoding and let their phone send out the vCard data encoded in this way... Unfortunately the Motorola doesn't seem to support that, at least with the Vodafone firmware.

I therefore transferred one by one all the addresses to kaddressbook and sorted them a little. Right now I'm looking for a way to transfer the entries to the V1075. kmobiletools should help.