Well there is no one, forcing you to use the premium extras... And there is a need to diamond related things to be checked and debugged as well.
Also as you know "Beta" is just a name, I am thinking more like the game ImperiaOnline version 5.0! And when Beta is over then the proper patches will have been applied. For example you go and buy (! yes some pple do that!) the new EA game Medal of Honor (another Call of Duty clone for me
) and you find some glitches and bugs. But you have already paid for this! Then after 2-3 months the game release a patch, then another and another... until the game is running perfect.
What I want to say with that?
You buy (if you want) diamonds and you decide when and if it is worthing to spend them! After the Beta is over, even with server restart, your diamonds will be there! Just like all the other games out there... BUT the "big" companies don't dare to say that the game they release is actually beta... they only prolong the alpha phase a bit.
P.S. A wise man told me "Never buy a Microsoft project until the second service pack is released, it will ruin you..."