In another forum I saw a posting that helped explain the differences between the Stihl models:
There are a couple of other things to consider here. STIHL makes saws considered for homeowner, or occasional use, farm and ranch or semi-pro, and professional use. They all have the same warranty, one year for homeowner and 90 days pro. I honestly believe they all are well designed and good value if you look at return on investment for run time, performance, and just plain fun and ease of operation. That is of course based on proper care and use.
So you have to decide on a price range and how hard you plan to use it.
The breakdown pretty much goes like this:
MS 170, 180, 210, 230, 250, 192, are light duty use. They have a clamshell or engine pan design, called modular, where the crankshaft is pinched between the cylinder and the engine pan, making the engine module, and everything else bolts to the module. The bar bolts into the plastic tank housing. This makes for ease of manufacturing and keeps cost down, so the price is lower at retail.
The MS 290, 310, 390 are designed the same, but have a heavier crankshaft and are considered more of a mid-range saw. All of these models have an aluminum engine pan, chrome or Nikasil coated cylinder, four open transfer ports, and plenty of plastic holding it all together. The bar has one bolt into the engine pan and the other into the plastic tank / handle housing.
The MS 270, 280 are more of a semi-pro model, with a magnesium engine pan and housing holding the crank in, and the bar, but still a clamshell design. These saws are a newer design with some more current engineering in them, and are a great performing saw with plenty of power and performance. I really enjoy running this model. The 290, 310, 390 is a much older design, but has plenty of power and a proven track record.
When you move up to the pro models there is a big difference in design, and they cost more money. The MS 260, the older 034 and 036, the newer MS 360, 361, 440, 460, 441, 660, 880 are all pro models, designed for logging or commercial use. Now you have a split magnesium crankcase, that holds the crank, and both bar studs, in a rigid configuration, with the cylinder held on with four screws, and a plastic tank housing and handle assembly. The pro saws have closed transfer ports. The older models have two ports, the 361 has four. Where this all comes together is that the 361 weighs less than a 390, and has more power with less engine size. It is engineered to a higher level of performance, and is a newer design. So if that is the size of saw you are after then is it worth the difference in price to you to pay for a pro saw?
Down the road for repair will also make a difference. I can have the piston in my hand in 5 minutes on a 361. It will take a complete teardown, just about to the last bolt, to get the piston out of a modular design. Will that matter if you only cut a cord or two a year? Probably not. But the labor and parts cost to have the dealer install a new piston and cylinder in a modular saw will usually exceed the value of the saw, even on a 390. But a pro saw it usually will not. And a saw used by a pro may get over a 1000 hours on it in a year. So it is worth the repair. .....
