Upgrading troops

Iv thought that once you have built 10k of 1 type of unit ,for example infantry, you could have the option to exchange all of these troops for an upgrade , 10k of your infantry taken away but from then on all the attack , defence and speed values would be doubled everytime you create more of that unit !
I think it could work because it would spice up wars however I don't think this could be applied to alliances
Please tell me what you think about this idea and your welcome to contribute to the idea and I will edit it in
Active on s54(true_lad) s82(kittz) and s83(minns)
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viewtopic.php?f=4&t=12083