I have just got the Kirk BH-3 too, it's a marvellous work of engineering! No more slippage when the main knob is tightened. It may be expensive in the short run, but the cost will even itself out in the long run. It's slightly cheaper than the Acratech too and comes with a universal plate (which the Acratech doesn't), so cost-wise you'll be saving around $50 there.