What you heard on other sites is completely true. SBR really is that crooked.
If you need any proof, just look at BetPhoenix's rating. Then look at all of the complaints and issues surrounding that terrible book. Then consider that SBR puts all kinds of minor complaints on their "front page" when it comes to a non-paying book like Matchbook, but not one BetPhoenix complaint has ever made the front page, no matter how major.
I am a Matchbook customer. Their management is kind of stupid, and some of the the things they do will leave you scratching your head, but Matchbook is a must have out for any U.S. based gambler. You can not beat their lines and they have great liquidity for most major U.S. sports (terrible liquidity for some others, such as NCAA Basketball).
If you want to know how good or bad Matchbook is, don't look at SBR's ratings (which are bought and paid for). Look at the SBR customer polls. Matchbook is consistently rated in the top 3.