Betking.io has a fairly long history of paying out gamblers, sometimes paying out thousands of BTC. I would put their trustworthiness in the same league of primedice.
I don't think using escrow is necessary in this case, although things can obviously change in the future.
ore-mine was paying for ~2 years,
I believe that just as how scam campaigns arent listed here, campaigns without escrow also shouldnt be listed
You're overestimating the role of escrow. It's a good practice and brings comfort to participants especially when signing up for new campaigns operated by new/untrusted members.
But it's not a guarantee of anything. The amounts escrowed are rarely enough to cover max possible expenditure (especially where there are delays in payments) and using escrow doesn't mean the business can't be a scam. There's also always a risk that escrow provider will run away with the funds (not sure whether it has happened before).
In judging campaign's credibility, it's best to look at the bigger picture and previous history. In case of betking (formerly PRC), they've already run 2 sig campaigns, have done number of high-value promos, they hold the biggest investment fund of all BTC gambling sites (around 3k). So the risk of them defaulting on signature payments is close to zero.