Check the tutorial video on Martelli's website....there is a reason for the difference in direction....no righty tighty, lefty loosey.
I saw Dave doing these demos last year at the Lancaster Show....and if you do it right, there is nothing to beat the Martelli rotary cutter.
But....I'm a bit confused....he told us the notched blades would not fit his cutter. Some of you have mentioned using this type. Perhaps that's why you're not totally happy with it. He, Dave Martelli, said to use the round centered blades.
I am making flannel rag quilts for many, many, many granddaughters...lol...and the 45 mm Martelli cutter goes thro the many thicknesses like butter. I can cut 15 layers of flannel perfectly....you have to use the right pressure on the ruler....their rubber black one is heavy and good, but I really like the clear ones better for regular minimal thickness cutting. I'm going to buy the 60 mm cutter at the Lancaster show in March, definitely. He gives us a good deal on some items....I'm considering some of the feet as well.