I think you should just get rid of merge mining altogether, it's clearly not beneficial to the pool, i'd rather have consistent 50% CDF and actually see some real returns, than a bunch of shitcoins which are near-worthless.
You don't have to mine other coins. There is absolutely no correlation between luck & merge mining whatsoever. With btc difficulty going through the roof, merge mining is an excellent way of increasing ones income at no extra expense - this is why directpool have now implemented it, as well as most other pools.
Peace
