Another question is how to distribute the staking rewards. If there are two investors, both deposit 1000 coins, and one uses "/cold 3000" to increase his effective investment to 4000, he now has 80% of the bankroll, and gets 80% of all betting profits and losses. But what about staking rewards? Should he also get 80% of those? Or should they be split in proportion to the actual onsite invested amount, since those are the only coins that are earning staking rewards?
You should not allow users to increase their staking amount for offsite coins. Offsite coins are not staked by JD so they should not be credited towards those users. That would allow double dipping as someone already pointed out.
As long as variable kelly is available for all investors, I can see only one problem with the kelly multiplier idea, and I admit it is minor. Whales tend to win or lose in streaks. So you should always use max allowable kelly and put the smallest fraction you can on the site. If a whale loses, great you rack up, if a whale wins, you only lose your amount on the site. So you'll see a lot of fluctuations in max profit.
Pretty minor, thanks for all your work to make Just-Dice such a good site.