The VTP clients will keep the VLAN DB as it was from the last update. You will not receive any new updates until the servers come back online. If you reload the client switches, they should also retain the last update. "sho vtp status" will display the last update timestamp and server.
My experience has been that you must clear the database manually, or write erase and reload to really flush it all. The persistence of the VTP database makes it difficult for some to clean-up without having good working knowledge of all the knobs and buttons in the IOS driven switches.
The transfer from client to transparent should also not affect your VLAN database on that device, as you are changing type and not domain where it would be desireable to gather new information from the VTP server.
Rebar
