Based on what I have observed, I think that Roobet is the best option currently thanks to their excellent rewards system and it is a great site for high rollers like you op. House edge of the dice game there is pretty low too and they sponsor regular contests.
Other great options include Stake as you suggested and Wolf.bet. I would still recommend Roobet over them though overall.
AFAIK house edge of the dice game at roobet is 2%, if I'm correct about it then I cant say that it is pretty low like what you say.
Most other dice sites has 1% house edge which is the standard house edge of dice in this gambling industry IMO, so I wonder how can you say it as pretty low.
No personal offenses to roobet, just wondering which other sites you use to compare the house edge. Freebitco.in?
Coming up to reward system, my choice goes to Stake. They have generous reward system coming from weekly and monthly coupon, reload, free bonus for some special events, rakeback, and many others.