It really depends on the pieces you have. Replacements is super picky about the condition of items so you are at their mercy. You pay to ship it to them and if you don't agree with their valuation then you also pay for return shipping. If you have the time and patience you will, by in large, get the best value by selling on your own via ebay. This takes a lot of time on your part but if you are about maximizing your $$$ then that is almost always the better option. Getting the best value selling yourself also require selling it piece by piece. Most people arent looking to but a service for 8 they are looking to replace lost or damaged pieces. The other big seller are serving pieces. A good compromise is to sell the typical place settings to Replacements.com and then sell the specialty and serving pieces on your own.
As someone who own service for 24
I know a bit about sterling silver as I had it valued for insurance purposes. I have crazy pieces like fish forks, tomato servers, iced tea spoons and poultry shears so I know way too much about this topic.