They are quiet props (PowerTech 4 and 5 blade). They are also smoother (less vibration). The more blades equals better balance which is less vibration. I also prefer the PowerTech cushion hub. It's so smooth to put the boat into and out of gear. Quiet, balanced, smooth, easy to turn the boat, amazing hole shot, fantastic reverse thrust for docking, decent fuel efficiency for extended range of the boat. I will end up with two of the SCE5 Modified Channel Surfing edition prop's.
They are sending me a new, anodized exhaust tube and diffuser for my SCE5 Modified. I'll wait a bit before I order a backup prop to let others get one.
I've been using my Yamaha SWSIi 3 blade as my backup prop. Earlier this year when I had to send the SCE5 back to PowerTech for work, I had to run the 3-blade for a couple of months. We went to Edmonds, in 2-3 foot seas in Puget Sound, windy day. I couldn't run the boat at 20+mph in the waves unless I wanted dental work on my back teeth fillings. Slowboating at 8mph sucked. The Edmonds/Kingston ferry was approaching, we were bobbing in the water with the waves, I was within sight of Edmonds. It wasn't a family friendly day as the Navy sailor in me came out (my mouth). I was frustrated because I knew I should be able to do 12-15mph and ride through that mess, but couldn't with only 3 blades. I was frustrated, and super excited when the SCE5 Modified came back a month later.
Here's a short video clip. This was filmed in Glacier bay, in the cockpit, with us underway doing 8mph, using the OFS4 (4-Blade PowerTech) prop.
It illustrates how noisy the prop isn't.