I'll tel you what's dragging: this thread!
For cruising in heavy currents, on a small boat: 3 blade-folding. I went from feathering 2-blade maxprop to 3-blade folding flexofold. Gained a full knot motoring and maybe lost .2kts sailing, which is unmeasureable, 'cause I probably "lose" more than that just chillin' and enjoying the ride! Get 3 blades. No brainer.