My hat is off to you LP, if I don't have the cash I dont go at all. If I go without cash, every coin I have been searching for, for many years, at every coin show I have ever been to, will be in the 75% off bin for sure.....
I keep going in places (coffee shops, boutiques, my kids jiu jitsu academy, bakeries) that have replaced traditional Point-of-Sale (POS) registers with Ipads and/or cell phones equipped with Square hardware and software. (https://squareup.com/ if anyone is curious) Really, most businesses that have started in past two years in my area NEVER had or will have a old school POS. Too big, too expensive, too much to maintain. I would think Square would be showing up at most all major dealers at coin shows, because it is so affordable, extremely portable, and the barrier to entry is very low. If you are a dealer with a cell phone, then there really is no excuse, assuming you want to take credit cards at all.
If you had no fear, why did you have two stashes? The OP asked a question concerning his safety, people responded ways to help keep from making themselves a target. Like don't keep all your money in the same place. Watch the parking lot, don't flash a big wad of cash. Seems like good advice.
I'll say Shoreline Washington. My brother (6'1" ~300lbs) got robbed at gunpoint for $15 that he received in change walking out of a store towards the theatre at night.
I have no qualms about carrying cash up to several thousand dollars, but I just have no reason to do so. I seldom find anything to buy and when I do it rarely costs more than a couple hundred. If it does cost more I have no problem using checks so why carry large amounts of cash? A couple of hundred is plenty. That tends to be a real problem. With the low percentage mark up, percentage the card company takes, and the fact that so many buyers don't want to pay sales tax and expect the dealer to absorb it it makes the dealers reluctant to start taking credit cards.
I really think that you are using anecdotal evidence as your basis for your feelings on this subject but that doesn't make it true. I looked up Shoreline on Neighborhoodscout.com and it is not a dangerous city. http://www.neighborhoodscout.com/wa/shoreline/crime/ Take a good look at those stats and then compare them to where I live, Atlantic City. http://www.neighborhoodscout.com/nj/atlantic-city/crime/ Nobody can doubt that Atlantic City is dangerous. But the simple fact is that you can avoid most crimes by not putting yourself in a position to be a victim. The majority of crimes in AC happen in specific neighborhoods, at specific times of day. By avoiding those situations, you greatly reduce your chance of becoming a statistic. It is my opinion, that most coin shows are not held at night in dangerous neighborhoods. In the rare occasion where a thief has decided to stake out a coin show, common sense measures like keeping two pockets, not flashing cash or coins, parking in a safe place should prevent you from becoming a victim.
You will probably get a better deal paying cash, as it costs 3%-6% for the dealer to use the credit card...which can add up fast. I have also never seen a credit/debit card used in a coin transaction. But I did join a bank the other day that is open until 12 on Saturdays...so I have that going for me. I would say, know the environment if carrying money is a concern to you. I always take as much cash as I can. I like to make a small purchase initially and let the dealer see a wad of $100 bills before I start negotiating on larger items, so they know I am a serious buyer. It might be unethical or tacky, but it was partially how I was schooled. I also look like a mindless schlub and can play dumb very well I use lots of "what is this" and "are these any good", while pointing to a MS 79CC $1. You just have to figure out what is right for you.