It's getting to be common practice in MTB. A lot of guys are running an aggressive Kenda Nevagal on the front and a fast rolling Kenda Small Block 8 on the rear, often in a more narrow width. I've never thought about doing that in 'cross but it could be a good idea. Aggressive tire up front, with a file tread in the rear. The basic thought being you need more control and bite for the front tire and the rear tire can slide out a bit without you going down.
Currently I run a set up sort of like that on my cross bike and often use it for mtb races. My cross set up is the Hutchinson Piranha in the rear with a bulldog in the front. I like it. Solid cornering with the front wheel and a nice fast rear wheel where I don't feel like the tread is dragging me down any.
That is exactly the set up I've been running. Pirahna in rear and Bulldog in front. I like the volume of those tires. But I do feel the Bulldog is a big drag in grass. Are you running them tubeless? If so, what pressure?
I am running them tubeless. I have been testing different pressures all week but am pretty comfortable with them at 30 in the front and 32 in the rear. The perfect amount of cushion while not feeling sloppy on pavement corners.
Tuesday I had 8X~6 min "hot laps" w/1:1 rest on the schedule. I did this workout on a local course that is mostlly grass and sidewalk. Two years ago I did the race with a mich. jet f&r and had wash-out issues in the sharp grass corners. Have a normal grifo on the front, and brought 2 rear wheels one with a normal grifo, one with a grifo xs (file tread) and alternated them each lap. Pressure was in the mid-hi 20's for all tires. Since these were "all out" there was no pacing, just as hard as I could go for the interval. The conclusion of this totally unscientfic study is that the xs was slightly ~6s/lap faster but more importantly, it felt better on the pavement sections and did not wash out on the grass even if I tried to push it. So on the grass with pavement, this seemed to be faster. One thing is to get out on your race set-up often and do some cornering at race-speed to really learn where the limits are.