It's an interesting change, which appears to me to be purely motivated by making more money. Nothing wrong with that, of course (and I'm sure bustabit and investing in the bankroll will remain profitable for years to come). However, 50% is squeezing investors a bit, and it hamstrings the potential significantly. bustabit has been my go-to recommendation for Bitcoin investing, but it appears I may have to reconsider. I'll be divesting my small stake in bustabit and deploying it back into flashflip, which keeps the commission model (thus giving investors a 25% greater expected profit on each coin wagered).
Nevertheless, good luck with everything.
Their EV isn't investors' only consideration when choosing a casino. A casino might have more favorable investment terms than another and still offer less expected bankroll growth if it can't match its competitor's wager volume. And in terms of wager volume, bustabit is one of the most popular Bitcoin casinos today. I couldn't find your game's wager volume anywhere but I'm confident that in terms of expected bankroll growth bustabit is still very much competitive despite the lower EV.
With that in mind, I don't believe that 50% is unreasonable at all and bustabit is still a very attractive investment.