Choosing the Correct Sized Sliding Miter Saw — 2014 Tips
The greatest central decision one must make when contemplating the purchase of a sliding miter saw is what sized blade would work best for your particular workload. The blade of a sliding miter saw is circular and either 10" or 12" in diameter.
While the saw, fastened as it is to sliding rails, has a longer cutting distance due to its nature than a drop-cut saw, the extra 2" can be either critically important or a superfluous excess.
For a woodworker that frequently works on projects that use larger lumber, the extra cutting depth is needed. Few DIY home workshops require this extra size and subsequent price increase. For decking and crown molding, the 10" sliding miter saw is quite adequate for at least 95% of the jobs around the house.
Make sure you don't confuse the tool you need for a particular job. While you might think a 10" miter saw will not handle large cross-cuts, remember, the preferred tool for these large cuts is actually a table saw. Used together, these two tools will provide almost all the cutting you might ever need. Trying to fit too large a piece of wood into a miter saw can cause instability, inaccurate cuts, and the potential for dangerous operation.
The price difference between a 10" and 12" sliding miter saw can be from $200 to $300. Before springing for the extra cost on a larger saw, be sure you need it. Even with the biggest saw, there will be the occasional project it can't do. If you are not often working on very wide and thick wood, save yourself some space and money by going smaller.
If at all possible, try to figure out what most of your work involves and size your tools according to what seems the best fit for your needs.