Possibly, but only if you are very light. Small Sibs sit lower in the water for a given weight than a bigger one, so need plenty of power to lift up onto the step, so to speak. Slat floors are generally fairly lightly built an so tend to flex with power and a bulge of water builds up under the stern, and slows the whole thing down.
Having said that, I had great fun with a floppy floored Avon Redcrest: I would put an oar stem to stern under the wooden floor to stiffen things up, and it would plane happily one up on 3.5 hp.
You really can't beat a rigid floor in a sib, preferably with an inflatable keel underneath it.
However, it's worth playing around with the little slatty. You never know.........