Just use a VPN - no big deal. TBH I wouldn't trust any of the other newer sites till they actually have been here an extended amount of time and have continuously shown professional behaviour and support. If you can't use PD, JD is pretty good - only issue is that CLAMs are relatively volatile, real pain in the butt if you want to gamble.
I do know that you can still play on PrimeDice by using VPN but this is not the case for this question since OP mentioned specifically that he has excluded both PrimeDice and JustDice. PrimeDice and JustDice both started as a new sites as well, which the competition was a bit lesser on that time. Eventually all new dice sites will get there, since the matter of trust is earned over time
Clearly means that OP is not looking for either PrimeDice or JustDice as an answer since he has excluded and know about it. So both of them is not an answer for this