I have 8 inch Powderhounds with 3 inch carbides, no studs. I don't think I'm typical of the guys on here, I'm am icefisher and I troll sloooow. I like the skis because they are insurance for getting out of deep overflow slush. They allow me to play around in the drifts and if the lake is windswept or I'm following tracks only the keels contact the snow anyway.
That said, the lake was slow to freeze and I've put on 800kms playing around in the bush. With the powderhounds on this isn't even the same sled it was last year. I couldn't do a thing on it last year. Now I am breaking trails on my own and the comealong hasn't come out yet. I know that due to its weight it is never going to be too fleet of foot in the deep stuff but so far, by going easy, I'm getting in and out of places I couldn't touch last year.
Directly to Al's question, I don't think there will be much difference between 1 or 1 1/4 inch keels on trails. If the snow is firm both heights will keep the rest of the ski off the snow. I like what the 8's do in deep snow and I know you will see way more powder than I will. I expect the only on a soft heavy trail would the 8's not be my preference.