TOPIC:

Well... problem is that 500-ish town can be claimed legally too... if some player joins later in game, towns also gets bigger over time even to 500 ppl then claims it and gets instant advantage - legally.... I think it wouldn't be a bad idea to put HQ restriction to 300/350 people instead of 500 so there won't be even possible to cheat this way ... also later joined players wont be advantaged... What is your opinion about this guys?

Pretty sure you can't claim 500+ towns, but you can claim towns just under 500 that already have enough houses to go 500+ (it takes 3 months for pop to increase after a new house is built), and there is a huge advantage in this. One simple option might be to disable automatic town growth in CB games.