Echo's are not popular here, no doubt about it. I was able to aquire most of the Echo line-up a few years ago, and have been running them quite a bit.
In general, they are OK. The reed valve 300, 301's and smaller top handle saws are pathetically "anemic". They cut so slow you could go back in the house and have another cup of coffee and a couple of donuts before they would get thru a 10" hunk of oak.
The CS360T is much, much better, except they use one of those rev limiting modules in it, making it difficult to dial in, but it cuts at least 3 to 4 times faster than the reed valve top handles. Out of the box it was WAY lean, and restricted at the muffler. A quick muffler mod and removing the limiting caps on the carb, and the 360 is right there for power and speed with the "high-end" top handles we've ran (and NO, we haven't heard the Echo "death rattle" yet, and we've got quite a few hours on it).
The CS-440 we had was a TURD, even after correctly adjusting the carb and opening up the muffler some. It was hard pressed to manage anything more than a 16" bar.
The 510's (we have two of them), are great saws. They are maxxed out with an 18" bar, but very, very well suited for a 16" bar. We have been running the crap out of them now for at least 3 years, no problems. As good as they are, I recently put one up against my muffler modded Husky 55. The 55 chewed up the Echo and spit it out. The 510 was so embarrassed, I had to put it back in the truck until the Husky 55 ran out of fuel.
Same deal when comparing the CS-670 to the Husky 268XPS. The 670 is OK, just a decent running mid-range saw, with decent torque, at it's limits with a 20" bar. The Husky 268XPS is a BEAST in comparison, and will cut nearly twice as fast thru anything as the CS-670. As good as the 670 runs, it was a JOKE to compare the two saws side by side.
Despite being down some on power, I still like and recomend the Echo saws. They are a real bargain if comparing price. Just fully expect to have to "fatten" up the carburetors a bit, and be conservative with bar length. If Echo recomends a 20" bar, an 18 will be a lot better.
We keep hearing all sorts of comments about lacking in durability. We have about a zillion hours on one of the 510's, and it runs flawlessly. I like it because it is light weight, decent power, and very, very thrifty on fuel. There isn't another saw in my line-up that will cut as much wood (smaller stuff) on the same amount of fuel.
Folks, I'm not posting to piss anyone off. Just to provide some real, up to date information on some saws we have tested.
I've worked on, and ran ALL brands over the years, and my personal line-up is made up mostly of older Husqvarna's. I like and use the Echo's, but you could take all of them and throw them down over the hill, and I could care less. I like running my Husky's a LOT better, and pound for pound they run equally as well or better than anything else we've tested, aside from some very NEGATIVE experiences with the later stuff, and the line made by Poulan.
If you just cutting firewood, and live in Ohio where I do, not to mention getting older and favoring lighter saws for small stuff, the CS-370 would no doubt be a decent limbing saw, if it runs as well as the other ones we've tested.....FWIW.....Cliff