I think many of us can emphasise with that situation of being ignored or not taken seriously in some or other store. The following doesn't excuse that, but in some ways it goes to mitigating things. This business does attract a lot of dreamers and tyre kickers. It doesn't help either with the preoccupation with price (both buyers and sellers) in what is essentially a boutique-type sales situation. It's a contradiction. Slashing big chunks off prices means selling high volumes to stay in business, and that's the polar opposite of what's required to do the full-service sales model of single speaker demos, home equipment loans and all the aftersales backup.
Overarching all of this is people, on both sides of the counter. We are complex creatures, full of our own contradictions that sit on top of the already-challenging problems of communication.
A lot of what you've written so far points towards a person who needs and should value the services of a demonstration. I've told you that and so has
@kitfit1. It's up to you whether you take that advice. If you spend any time in dedicated Hi-Fi forums you'll get the same message. None of us are saying this to waste our breath. It does make a difference when you're buying new. Now, here's something to consider; if you're set on buying blind, then why buy from a dealer at all? Save a heap of cash and go buy second-hand instead. Depending on the age/condition/desirability of the speakers you could either get a much better front+centre package, or buy a complete set of 5 speakers for what you plan to spend on just a new stereo pair.
Buying used means you already know the speakers are run in, so you'll get an instant impression of what they really sound like. All you have to do is make sure they're positioned to give their best. There'll also be a bunch of reviews and lots of opinion on the most popular speakers, and that means both that you can find out the good/bad before you go searching, and also weigh up if the public opinion matches your own experience.
Buying used does come with its own issues though. What you save in money you spend in time. You're also gambling that what you're being offered is up to par, and by that I mean that the pictures you'll see of the gear accurately represent the real condition. This is why you should always go to view and listen to the speakers before parting with your cash. You'll have realised at this point that this can all be very time consuming. It is. There's no two ways about it.
Where you're cash rich but time poor then buying new from a decent dealer is the quickest and surest way to get the right product. Buying blind carries a much bigger chance that you end up swapping the speakers much sooner, and that's a great way to throw money down the drain. You'll buy something else too: Restlessness. That constant nag, even after the usual buyer's remorse has faded, that there's something better.
For the cash poor time rich people then second-hand is a great option.
The issue of finding a good dealer can be tricky though. Even though I'm in the trade, I still have a relationship with a couple of dealers whose judgement I respect and trust. If I was looking at something new for my own music system then they'd be the people I would go to. They're not on my doorstep though. They're both a good 30 miles away, but the journey is well worth it.
Find a dealer, even if that means travelling. Be straight with them; say you're looking at new speakers but not sure where you need to pitch the budget to make an appreciable difference, so you'd like to bring in your speakers to compare. If you like what you hear then you'll buy.
You mentioned bi-amping the Yamahas. Have you ever wondered how you can really bi-amp from one amplifier? The speakers are drawing all their power from the same amp which runs counter-intuitive to the idea of bi-amping which means to run from two (or more) separate amps. Yes, the receiver may have the feature, and I don't doubt that it sounds different, but that's no necessarily the same thing as sounding better. It's just a thought.
