It's somewhat risky for Bonneville, and Mike's email shows some of why, even though FM talk has had some good results in other cities, especially by Bonneville. They're hoping of course, to make a dent in NPR at KUOW, KIRO's real competitor, though it doesn't show in the published ratings.
KIRO, however is a heritage station whose AM news and talk format is 80-something years old: it's still an unknown whether AM people will change their dials.
(The move has set off a sports-radio war in Seattle, with 710KIRO duking it out with KJRAM, and Everett's KRKO. We're trying to get interested, but it'll be hard to stay awake for that lumpen cat fight).
We've had problems that could effect how much we listen to KIROFM. In one main listening area of our house - the kitchen - KIROFM is not very stable. About half the time reception is OK only if we're standing right next to the radio.
Another problem is that mostly because of the damn commercials, we listen to several AM stations (KVI, KIRO, KTTH, KOMO, KPTK) at once, especially in the car where we can push the buttons. We dial around at home too, but the buttonless counter top radios are inconvenient to switch between AM and FM.
We probably won't be going to the trouble of getting an FM antenna (we're the types who go to the least amount of trouble) which means we'll be listening to less KIRO.