I haven't tried the K&K, but if it does not feed back like mad it'll be the first contact pickup ever not to do so. I also find that contacts sound a bit thin and lacking in round bottom so are not good (to my ears) for open tunings - but I do like a big roar and your ears may differ.

I-Beams sound nice and round but tend to feed (and have batteries).

Headway snakes sound nice, but have batteries and will require change to the saddle slot.

B-Bands sound quite natural (maybe a smidgeon of B-emphasis) and are so thin that it may not be necessary to modify the saddle slot but have batteries.