I've never used a THX Ultra 2 processor or receiver for the reason you mention - cost. The cost premium tied to the Ultra 2 products that I might have considered in place of my Outlaw is significant, on the order of 2x or 3x or more. There would be some other benefits aside from THX, as one would expect from that sort of large jump in price, but for me the benefits offered by those more expensive alternatives weren't enough to justify the added cost.

Even lacking THX Ultra 2, the Model 990 is a very competent processor at a relatively friendly price ($1100 is still not peanuts, but compared to many of the alternatives it's a great value. I'd recommend giving it a try - the opinion in this case that matters most is yours, and the best way to make up your mind is to hear it. I think you may be pleased.