I have used a huge number of different sharpening systems. The Timberline creates a very sharp chain but I have difficulty getting the left and right hand cutters to be equal. I did not like the 12V Dremel style sharpener that I used. The Granberg style sharpeners work well but I found them slow. I can free hand but I am not the best at it. The nicest hand guides for in field use that I have tried are the Husqvarna ones, for example:
Husqvarna Chain Roller Guide Combination .404 3/8in | SHERRILLtree They are very fast to use and do a very good job. I had terrible luck with a bench grinder - I tried special lubes and special wheels and only took multiple very light cuts on each tooth but I could always see the tooth get hotter than I wished. I have drooled over diamond sharpening blades for years and finally bought one from Diamond Wheel, Inc. to put on my Oregon sharpener. Should have done it years ago. Very sharp chains that stay sharp for an extremely long time. I think this is partially due to the diamond cutting cooler and I took the time to even up all of the cutters. Normally, I would either swap chains or hand touch up after every couple of tankfuls. However, the current chain has cut well over 15 face cord without even touching up by hand sharpening. I find that truly amazing given that I did not brush off the dirt etc where i was cutting like I normally do. I should swap the chain out now since the chips are not quite as large as they were but it is not creating dust yet. I always buy Stihl brand chain - it seems to stay sharp longer than the other brands I have used when in a pinch. Ken