I am a Dealer so I do have some perspective on this. First of all, there is NO Standard for home auditions or trials. I know major, well-respected dealers who charge a fee for a home trial and I know many that have some other arrangement. The one factor that IS most prevalent, as many have said here, is that IF you have a relationship with a dealer and are a proven customer, then yes, you most likely can borrow equipment for a short time on "trust" with no fee. This is how I treat my best customers.
HOWEVER, if you are unknown to the dealer, then you can't expect them to just "loan" you expensive equipment for audition without some type of protection for the dealer. On example is to pay in full and then have the right to return and refund if you decide not to purchase. But, what is wrong with paying a reasonable fee for the opportunity to listen to an expensive piece of equipment if you don't buy it? Do you know of ANY other business that would let you just "borrow" an expensive item for the weekend? Maybe your local jeweler? The Apple Store? Despite what some here may think, there IS a REAL cost of opening a new product's box and having it out for audition. That product can no longer be sold as "new" and now needs to be sold at a lower price just because it isn't sealed. That's why dealers may charge a fair demo fee (if the customer doesn't buy) to compensate in a small way for the lost revenue. And, sorry- but this is in NO WAY similar to taking out a car from a lot on a 15 minute test drive or sampling a "taste" of a slice of bologna! Give me a break!
This whole concept is subject to substantial skewing if that equipment is very expensive, delicate, or in short supply. It's one thing to get a loan of a component that costs a few thousand; it's totally another to expect to borrow a very expensive high-end component. In this case, the OP is talking about a $10K+ component from a dealer who does not know him. I know most of the Grimm dealers and they are all reputable and customer-service oriented.
This debate has unfortunately come about due to the unprofessional and unfair practices of more than a few (but by no means the majority) audiophiles who make a habit of borrowing expensive equipment from dealers solely because they are "bored" and want to try out some cool new component; or, want to make a hit with their local audio group and bring in a "demo" of a hot new toy. They have no intention of ever buying. Or, even more common, they borrow a component from a dealer, decide they like it, and then call every other dealer for that product in the country, bid for the best price and buy it at the lowest price. Meanwhile, the dealer that invested in the demo and loaned it out (and did not have it available for that demo time) plus spent time answering lots of questions does not get the sale and eats the cost of the demo. That's plain unethical in my book. If you want to call around for price, then have at it and THEN ask the lowest price dealer to send you a unit for audition FIRST. See what happens then!
This all goes to the root cause as to why there are fewer and fewer real High-End dealers left. Ultimately, many buyers buy only on price as opposed to the TOTAL VALUE that the dealer brings. Customer service, when done right, has a cost, as does purchasing demonstration gear so customers can listen to it. We are seeing the commoditization of the high-end industry. and eventually, there may only be online retailers left. Such a shame!
Finally, I am not questioning the OPs facts, but perhaps there is a big misunderstanding about the "5% for 1 hour" thing??
