Would a coin shop even be interested in "modern " silvers? Is that what you mean by "junk form"? As opposed to trying to get the 2.5grams silver equivalent for it?
The problem about exchanging up to bullion coins is that they cost a premium on top of their silver value. If you want to save coins for their silver value for the sake of saving precious metals, the "junk silver" category is nice because they are coins issued by a government with a known silver content - US are 40% or 90%. As long as it's not a key year (low mintage) or error coin, it's value is clearly based on the silver melt price. Dealers don't melt them down anymore because they can simply be sold since their PM content is a known amount, so you can buy or sell them at a price close to their silver content with no extra premium.
The flip side is if you decide to collect American Eagles or Canadian Maples those coins sell at a premium price over their silver. That price can vary by coin and mintage, but let's assume a silver value of $30/oz. You buy a 1 oz .999 fine silver bullion coin, but the dealer slaps on a premium of $4 - $6 per coin. You end up paying $34 - $36 per oz than if you would have bought "junk silver" that could have been acquired for melt value - $30 per oz.
If you find the 40% or 90% coins through CRHing and only pay face value, then want to trade up that is up to you. You would probably never recoup the cost of that extra $4 or $6 dealer premium if you later sell your PM's for profit. But if trading up and keeping 20 1oz .999 coins as compared to keeping 136 40% coins (to keep 20 oz) makes you happy, then that's of course fine also.
Some collect for numismatic value, and others as a pure numbers game to squeeze every cent value out of the silver that they acquired at face value. Personally I'm the type that likes to get silver at US face value and don't like paying $30+ per oz. To each one their own.
