I would never trade my Whistler Pro 58 for anything else under $250, except the Pro 78 (adds speech). I have never had good luck with Cobra out of the sevenish radar detectors I've tested or owned. This whistler has caught a cop a mile down a curvy road, and about a mile and a half down a straight stretch (just the other day, not too many straight roads out here).
Just remember, radar detector doesn't mean drive fast (often)
. It'* just a reminder that there IS a speed limit at the time that counts.