IMHO, I think the THX cert thing is extremely over the top over-rated. To me its a gimmick for the general public to buy a product.
As for Crystal Acoustics, I've never ever heard of them and I did A LOT of research over the span of almost 2 years before I bought my speakers and never onced ran into any information about Crystal Acoustics. I am not saying they are not legit but for the price they are asking....I look elsewhere. Better to be safe than sorry.....Plus resale value is always much higher trying to sell a brand that people are already fimilar with.