I've seen several reports here that authorized dealers (including GC now) are happy to order one for you to try but it's not the same as being able to try at least a couple of a given model or A/B different models when one is simply exploring options to narrow down the search.
Not only that, but I wouldn't ask them to get something in just to try it. And, I'm not sure how others buy a guitar, but I usually sort of "sneak up" on the purchase. I don't decide: "You know, I think I will buy a $3K guitar today." Nor do I just drop in to GC while my wife is at the mall, see a guitar and think: "Wow, I'm taking that home with me today!"
I start by thinking about a guitar. Maybe I've seen it somewhere. Maybe I am thinking about some future performance, and I am needing a new sound. And I start looking at things online. Ask for advice on forums. Read reviews. Then stop by some place to play it. That might go on for a couple of visits while I alternate between talking myself out of it and talking myself into it. Then I make up my mind and buy it. Or not. And that's the problem, not knowing for sure that I actually will buy it, I can't justify asking them to get it in, and maybe be stuck with it.
But I am not sure that it would be a motivator for GC to know that. If a Guild in the Martin/Taylor room sells, that probably means a Martin or Taylor didn't. And my guess is that they would prefer to move the Taylor and Martin guitars than the Guild.
Interesting question, one would think a sale is a sale and the unit generating the most profit would be the preferred sale, BUT:
I'm reminded of volume threshold rebates that were available to dealers when I was in the car biz (sell 50 units of a given model in a month, get $200.00/unit back), so it wouldn't surprise me if similar deals are offered to them by makers like Taylor and Martin.
I would think there are spiffs and kickbacks when you are moving high end brands. And I would think that Guitar Center also gets a group volume discount that is helped by all stores trying to move certain models. I could be wrong.
What I would do (I think. IDK. I'm no guitar manufacturer!) Is offer stores a "Premiere Guild Dealer" option. To those stores, I would offer two types of guitars: Guitars for the show room, and guitars for the stock room. The showroom guitars would come with a 90 day return guarantee. (Or some timeframe...) If you didn't move them and wanted to return them, send them back, we pay for freight. No hassle. If you ended up selling them, they would have a lower profit margin than the stock guitars. This encourages, one for show, one for go. But if you wanted to stock Guilds and see what would happen, you would have limited risk. The returns I took back from dealers, I would work out a deal with MF or Sweetwater to sell for us under the "slightly used" category, and give them a chance to grab attention with special deals.
For the Premiere dealers, I would have more than just a banner. I would do what Apple and Samsung are doing in Best Buy stores, I would stage a mini store front. I'd have a flat screen TV playing the "Guild Story" videos, and I would have beautiful 4 color brochures available (like car dealers do) that let people take home something while they are trying to talk themselves into a $3K purchase.
But like I said, I know nothing about the actual business of selling guitars. What I do know is that it is rarely a question of: "May the best guitar win." And people tend to be brand loyal. "I'm a Taylor guy," "I've always liked Martins," whatever. You need to work to get people to try your models out.