So far my STi has been a really great detector, much better than my X50. STi is still growing on me, so maybe one day soon I will trust it as much as my Escort original 8500. My STi's range on K and Ka police radar seems to be really good and unlike my X50, the Ka range seems to be consistent.
So far it seems that Bel has done a really good job with STi and it is a detector worthy of serious consideration if you are in the market for a new detector with money not being an issue. I'll keep you all posted after I have more experiences with my STi.