Recognition of ICCS is not a problem among high-end American collectors of Canadian material. But the best stuff inevitably gets cracked out and sent to PCGS for Registry purposes, TrueViews, better holders, better liquidity among less knowledgeable collectors, etc. For coins grading $500 and up, $50-$75 dollars per coin isn't an outrageous amount of money for the services PCGS provides. Not to mention some of us believe they are more competent graders (copper, problem coins, authenticity, consistency at Mint State levels, soft strikes).
Numismatic cataloger, writer, and researcher.