alot of radar detectors work, but the difference is that some go off with alot of false alarm, and misses some real ones. but the theory behind is are pretty much the same, it all comes down to design and ways to filter out false signals. i had the cobra before, they definetely work, but you just need to know how to read the right. it would always give me a stronger than usual warning when the threat is real.
since that one is stolen i've been doing some searching too for a new one, and i found that it comes down to the passport 8500 and valentine one. i've talked to alot of owners on both and they seem pretty equal, but a good suggestion i've heard from many of them is that both comes with 30 day money back guarantee. if you can, just buy both and test both of them side by side and keep that one that works for you. just bear in mind that police varies their radar state from state, so what works for one might not work for you.
personally since i am lazy, i think i am just going to buy the passport 8500. only thing holding me back is the price i am still waiting for a price drop or something. i mean they've been out for a while now.
btw, valentine one in my opinion is more fancy hence the extra price tag. but you can definetly have more fun with it (ie. custom installation etc)