Product Line Predictability

I've been doing research for a new pair of mains and a center. These forums have widened my perspective greatly and I am starting to see a lot more choices. I am running into a problem of not being able to even see much less hear all of the speakers at the local dealers. I keep hearing from the dealers that the sound is consistent throughout the same product line but the higher end models are just more dynamic. I have not been able to find B&W 803's, Vandy 3A's, Snell XA75s, but everyone has one step down from these and a "trust me you'll love em" for the more expensive models. So how much can you trust the product line? Why don't dealers carry the better models?
It costs too much to keep a lot of higher end product on the floor at most dealers. They prefer to keep lower priced products because overall, they will sell more of them. Higher end stuff sits a lot of times and is hard to move. It's not everyday someone plunks down $3500 for a set of Vandy 3A Sigs or whatever. The internet has changed the playing field for expensive speakers and so forth. Some folk listen at the dealer and then search for the best price new or used. I bought mine without actually hearing them based on a combination of factors and people I trust. I wasn't disappointed.
Most speaker lines do have a family resemblance. In the Vandersteen line, for example, more money buys better transparency, ability to play louder and somewhat better bass response. The sound is very similiar. Same goes for the B&W line but it seems better bass is the rule of the day here along with a little better transparency and things along that line. The cabinet proportions grow as well.
To sum up, generally if you like the lower priced products, as you move up, they are usually better. One caveat to this theory though-HA!- It's not always true. Sometimes a designer gets one speaker out of the line right. The rest come up short. In this case, a little research might serve you well.
I have had good luck moving up the food chain with most manufacturers Examples I went from a Mcintosh mc-300 to a mc-500 and now a mc-602 each time I had not auditioned the replacement as for speakers I went from Thiel cs-6's to Thiel 7.2's again with great results as for digital I went from an EAD Ovation to a Theatermaster to a Pro 8000 and now a pro 8800 again no audition and reasonably good results and finally cables from Nordost first Red Dawn's then SPM's and finally Valhalla's. I think in my case I really enjoyed what I had so the transition up the ladder built on what I enjoyed and added sufficient improvements.These are very specific upgrades based on gear that I had in my system for a while not a short listening session with the hope of a more expensive piece sounding better, I would not test drive a Jetta if I want to purchase a Passat or a Phaeton
Larger, more expensive speakers in the same manufacturer's line will not necessarily sound better in YOUR ROOM. I have heard all kinds of B&W's over the years and more expensive did not necessarily mean better sound. If you've been reading these forums, you'll have heard that some people prefer the Nautilus 805's and 804's to the bigger models for various reasons, not all of them having to do with room size. For speakers especially, I would not buy without hearing them first, at least in the dealer's showroom. You can end up spending a lot of money and being very disappointed.