Ripping chain is a generic name for just about any chain that has a top plate angle that is less than the common 25-30º toplate angle as used in cross cutting chains. The top plate angle used in ripping chain can vary from about 15º downwards.
Theoretically rip chain can provide a
1) smoother finish and
2) less chain vibration since the cutter does not dig in as far sideways as regular chain and should
3) a slightly thinner kerf which should lead to
4) less strain on a saw and
5) faster cutting.
What I find in reality is that 1) and 2) are correct, especially 1) if a semi-chisel chain is used. If you want to see extreme chain vibration try starting a rip cut using the full extent of a 60" bar with a regular top plate angle chain - the bar oscillates up and down about +/- 1/4" in the middle from this effect and makes for a messy start. The anti bar sag device really helps keep the bar steady in this regard. Chain vibration is less obvious once the bar is buried in the wood because the bar prevents this extent of vibration. Dropping the top plate angle to 10º makes a big difference and it feels much smoother all the way thru the cut. This effect is generally less noticeable on smaller bars.
3), 4) and 5) are less obvious because the kerf difference is very small. In addition a low top plate angle is also cutting woodfibres fully at high angles so the cutting action is mostly chipping, whereas an angled top plate has some slicing action which helps cut fibres. Chipping requires a very sharp cutter so as soon as the chain goes slightly blunt, rip chain is definitely way slower. This is compounded by users that buy new regular chain and gradually convert top plate angles cannot always sharpen their chains as well as a new chain so reckon the rip chain is way slower.
Another key factor in chain sharpening is keeping the rakers at the right depth and this is not a constant depth (eg 25thou) below the cutter. The wider the gullet, the lower the rakers should be. By the end of a chain's life my rakers are 45 - 50 thou below the cutter. Then you will see the rip chain can cut closer to as as fast as regular chain.
You can mill on a regular basis with regular chain on a small saw - thats what I have dome with my 50 cc plastic homelite with a 20" bar for several dozens of shortish hard logs. Like adkpk says, I wouldn't push it on long logs but if you take it easy it can be done,
