We now operate with two BTC pools - mixed and aggregated.
I don't know what to think about this because I don't like to see bitcoin being divided and there is always a chance of getting different prices, higher aggregates and lower mixed.
After doing some testing I didn't see any difference in price on exch, but I was wondering if this could happen or not?
[...]
There may be also a third option if we make 2 separated pools for mixed and aggregated coins and let users select which pool to use for their output, however it's a lot more complicated to implement and maintain.
Maybe this compromise would work best for everyone, if you can handle extra complexity.
Nobody likes, however the reality is that most mixers advertised on this forum do that and most users seem to be fine with the concept of separate pools (i.e. mixers that send you coins from exchanges and proclaim them as "clean"). eXch is an exchange and it's mandatory for us to have a static Bitcoin address, however, in fact nothing changed for those who prefer our original operation mode., since the "mixed" pool remain there.
There won't be any cost impact at all.
You can guarantee as much as you like, but centralized exchanges can still confiscate coins whenever they want

You've misread the whole statement. There is no part in the whole paragraph where we guarantee someone won't be able to confiscate your coins. We only guarantee a good risk-score in *our* aggregated pool.