Depends on what your view of the future of PMs are, the future of the numismatic market, and your personal storage needs.
If you think that silver's price should be $7-8 an ounce, then chances are you'd want to sell. If you think that silver's price should be $45-50 an ounce, then chances are you'd want to hold on to what you have, and then buy.
In general, if you trade 40%ers for 90% or .999 silver, you will lose some silver in the process, but if you've only got a small SDB or vault, it might be worth it for you.
It also comes down to personal preference if you deal with numismatic (coin collector) value or not. Myself I try to buy some cheaper numismatic silver when I can, even if I get slightly less silver. For example, I'd rather have walking liberty or Barber halves, even in lower grade than a generic '64 Kennedy. Some people have the opposite opinion, wanting the higher silver content of the pristine Kennedy over the lower silver content of the worn older coins.
When it comes to buying bullion people have different opinions. Some people prefer to get generic .999 rounds and bars. Others prefer to buy Silver Eagles. Still others prefer to get bullion coins with collector value such as buying Britannias or silver Pandas.
Since none of us have a crystal ball and can tell you what the silver price will be tomorrow or 5 years from now, nor can we tell you what the numismatic market will be like in 5 years. Will Morgan dollars become red-hot? Will British coins plummet in value? Will Roosevelt dimes start being collectable?
The best advice is to follow what YOU think the market is going to do and make decisions based on that rather than worrying about what others think the market is going to do.