I have tried to convert nuvi 2789 (HWID 1932) to dezl 770 using hybrid firmware (boot.bin from 27x9, fw_all.bin and resources.bin from dezl 770), but without success. I have had some message on screen with "mismatch".
After thath, I have used WebUpdater and "repair" nuvi 2789 to original state.

On the second try I have used full dezl 770 firmware (out.rgn) and I now have fully funcionall device dezl 770.

In next weeks I will test device. I will share my experinces with others.

Thank you very much, Butters.