I have the same idea and I already have the database in RAM. Now I use automatic backup every 5 minutes so that I can have at least 5 minutes old copy of the database in case of power failure.

The main reason I placed DB in RAM was to speed up the read and write operations. The problem with shadow will be that write will slow down. Big plus for using shadow is that I will remove that auto backup I use now and just copy shadow file to RAM on reboot.

Doychin