I haven't used 1xbit before but I also haven't heard that many good things about them... I think you should just stick to the books everyone uses and talk about here. I've been using Heritage Sports and it has been great so far. I also recommend everyone to look for reviews made by professional bettors. Bookmaker's Review has a rating guide just for BTC sportsbooks and betting sites and it's a legit site so, check it out
https://www.bookmakersreview.com/best-sportsbooks/bitcoin/ hope this works!
When it comes to choosing a casino or searching for information about the credibility of a gambling platform I always rely on the reviews from members of the forum and since bitcoin talk is full of so many casinos one can easily detect reputable casinos, just by reading through the variant threads and seeing the casino response to users problems and feedbacks
Reviews coming from reputable members and other high rank users with proper review so its really good to make this as a basis upon choosing a casino since like 1xbit they are paying some shill to boost up their popularity and this is totally bad for newbies who doesn't read anything before starting to play on some casinos. But guess their reviews gotten by forum members can help since for sure it will create doubt for people who do research about their reputation.