I've used 20nk for 9 months & they have been great chains ... I run 16" bar & 8pin rims on my PP346 & PP5100s. I have run 3/8 & .325 semi & full chiz on both & I will stay with the 20nk.
I noticed very little differance in cut times between these four chains...
You will notice a big differance in the semi's holding their edge over a full chiz. Twice as long ? no but close ....
You will notice more vibration in 3/8" compared to .325 on these saws (346-5100) and a big differance in how a 3/8" jerks small limbs (3/4" to 2") out of the way insted of cutting them. The .325 never seems to kick limbs away, and yes I keep rpm's up, way up ....
I use a Max grinder and pull the clamp rail to me at 5 to 7 degrees which gives it a hook on 20nk. I think this helps a bit ...
I cut a lot of tops of downed hardwoods, that's why I owne two nice, fast "limbing saws" , and use .325 chains. ... 12" or bigger, go get a bigger saw ...
Also, the PP5100s is no PP346 ..... The 346 (45cc) is a step above the 5100 in speed & feel. The 5100 is very nice but just not a 346 ...
Both are ported correctly ....