We're thinking more about a certain percentage of the Gold equivalent net worth of the player.
makes everything linear ,better cancel alliance researches than making something thats just proportional to size.Donating should be critical,but with protection from cheating.Heres why : if someone wants smaller alliance,and a bit more wars,they need to sacrifice gold to do it.but if his evil neighbor wants to farm and exploit others ,thats ok too .but if someone quits ,and sells army and gives 10m which is more than entire player dontation log,that spoils balance.
Im just saying,donation system ,and 4x factor for more expensive research level is good.just get rid of cheating.Even increasing factor to 5x would be great,encouraging ppl to be in alliance with ppl they really like,not because treasury ,when they realise that huge research levels are just not worth it.