Hi Dan,
I just bought a ECHO CS-4400 off of ebay. It has slope advance ignition. I thought that it would include a bunch of additional electronics, when I took the saw apart I found a flywheel and coil simular to other saws. The big difference is that it has three magnets instead of two. The flywheel is 3 15/16" and the coil is mounted on the saw frame. The engine is the one used for the BME 44cc power house, so I am looking forward to testing it with a prop. I ran it in the saw just to confirm the it was a good motor. It had easy starting even with a fouled plug and good transition. It will be interesting to see any difference with the slope advance system. The G-38 and some Redmax saws use three magnets in thr flywheel. I am going to make a bracket to mount the coil. I would like to install a CDI ignition later.

Regards, Dave