I will answer my own question:
I did a restore of the vcsa to a version prior to switching off DRS/delete of the resource pools and they where indeed restored as i had hoped. So they are indeed saved internally in the VCSA vm.
The resource pool snapshot mechanism on the other hand was totally useless in this situation as it merely creates a resource pool with the same name as the old one and moves the vm's that were in the old one back into it. It however does NOT restore the exact same resource pool with the exact same id. (which is what i needed in this scenario)
Hope this info can be usefull to someone finding him/herself in the same situation.
Greetings
Perre