The advantage is that much thicker and wider boards can be cut. This is the clear choice for the pro, since it offers unsurpassed accuracy in cutting angles on most commonly sized lumber, boards AND mouldings. Compound miter saws tend to be quite a bit more expensive than standard miter saws, and compound slide miter saws even more so. If you plan to do lots of mouldings or are willing to spend a little more for the best tool, it will be worth your investment. As far as the best way to attach crown mouldings to the wall, finishing nails are best for wood mouldings of all types.
Screws are difficult to countersink, especially when working with crowns.
There are now some plastic mouldings that look like wood when painted, and these are light enough that gluing with a latex adhesive caulk is recommended, but a few finishing nails are still needed to hold them in place until the caulk dries. Tips, hints, links, and surprises, delivered right to your Emailbox. There's even a free weekly email newsletter. All rights reserved unless specifically noted. All advice should be weighed against your own abilities and circumstances and applied accordingly.