So I bought the Echo CS-620 and ran one tank so far.
Feels heavy when hauling to the cutting site, but well balanced when cutting with the 24" bar.
I will say it is a world of difference faster on the bigger Ash trunks than the 490.
And I felt less worn out while using it.
Good power, didn't bog down in the rotted core of one trunk like the 490 would.
Noodled a smaller, 2 feet long by 10" or so Ash crotch, fast, and NO clogging like the 490.
Now the 490 will be used for smaller stuff and as backup.
I might even try and get the old craftsman 49 cc working, not sure what is wrong with that yet. Could be carb or coil.
Didn't see spark, but have not spent any time with it.