[dogscoff]

Surrendering could be balanced by making it less of an immediate benefit. For example, newlay acquired ships could be unavailable to receive fresh orders for a turn or two. New tech levels could be dripped through to the receiving empire over the course of several turns. This would give other empires the chance to seize some of the surrendered booty before the receiver had a chance to consolidate it.

Oh, and I heartily agree with the option to refuse a surrender.