I agree with the above posts. Either can be very effective. I use floats and jigs or bait almost all the time on the Kalama. In most situations, I never have to go more than 6 feet under the float. It seems like most of the time as little as 2 to 4 feet is where I catch the majority of the steelhead I catch. 2 to 4 feet can be handled well with a shorter rod (9 feet?), and moderate casts. I use a nine foot rod and a 9 1/2 foot rod. Longer is definitely better, but with all the foliage out, long rods and long leaders can be a pain in tight places.

In water of consistent depth, where the strike zone isn't overly deep and you have a long enough rod to handle the leader you want to cast, fixed floats are probably better.

With a fixed float, your float won't run down the line and pull your offering shallow if you get drag on your main line or at the end of a drift where you want to swing or hang your jig, etc. You can prevent this somewhat when using a slip float if you use a barrel swivel at the end of your main line, with a leader tied to that. But, of course, this restricts your minimum depth to the length of the leader. Otherwise, you can keep your offering at depth during the drift by keeping drag off your line, which is always a goal anyway.

Many times, I use a slip float just because it is so convenient. Depth can be adjusted rapidly with a combination of slipping the float and adding or subtracting split shot. When you get the depth right and see the offering gliding with the current in the strike zone and staying in the water you want to fish, you just know why this is such an effective way to fish. If the bottom is a rock garden you will spend your time fishing rather than hanging up and retieing.

You'll have good success with either and both have their uses.

Good luck!