I believe that coin collectors will tell us that any abrasives (toothpaste, baking soda) are a bad idea. I used baking soda and water to make a paste that I rubbed on my silver dollars for years. Sure, it made them shine, but it irreversibly changes the surface of the coin. Go to a coin shop and look at a pristine silver coin. It's really not what one would call 'shiny'. It has a slight surface texture to it that is damaged by abrasive treatment.
I recently bought a gaff to match my Morgan set from Jamie Schoolcraft (incredible workmanship! look him up at http://www.coingaff.com
) and it doesn't match my coins because I had 'shined' them. Now I'm forced to either baking soda my gaff (which I refuse to do) or replace my set.
I think it depends on the condition of the coins to begin with. If you start with old, worn coins, then I don't think it matters what you do to them (and the baking soda method is as good as any). But if you start with a coin with a good surface, I'd hesitate to go for a glossy shine.
I suspect that a trip to the coin store and a chat with the proprietor would yeild excellent advice.