I still wouldn't buy new without a demo.
Look, Hi-Fi dealers are in a pretty privileged position. They get fat margins on Hi-Fi gear because it's a boutique business based on high levels of customer service. The margin pays for having demo facilities and giving customers time to audition, and then offering home set-up of the purchased gear. It used to be that no specialist Hi-Fi gear couldn't be sold mail order for exactly these reasons. If you're not going to avail yourself of these facilities, why give the dealer their fat margin for doing little other than processing a credit card payment?
Where you feel your only option is to buy blind as-it-were, then I'd recommend buying used speakers. You'll be buying on the same blind principle, but avoiding the sort of fan-boy hysteria that can surround new products. You may also find yourself looking at older models. This can bring certain advantages. There'll be a broader range of professional and end-user reviews, so any quirks or issues will be highlighted. Of course the other benefit is the cost saving. You can either buy speakers equivalent to the KEF and B&W options, but at a fraction of the price. Or you could use the same budget to buy higher-spec' models. There's a lot of flexibility.
Buying new speakers mail order, and then auctioning at home, is really tricky. In order to listen critically, new speakers need time to run in. With some, this might take a couple of weeks or more. You'll also need to spend some time playing with the positioning to get the best results. By the time they're ready to be evaluated, the distance selling window for a return has closed. You could be stuck with speakers that you're never really happy with. The option then is either living with them even though they don't make you smile, or selling them on at a substantial loss before taking yet another blind gamble. Does that seem sensible?
Buy used. Try. Sell on again if they don't give you goosebumps. You may lose a little money, or break even, but at least you'll find out what works for you and what doesn't.
Hi-Fi shouldn't just be 'some better sound'. It should give you shivers. You should be like a kid on Christmas morning; that level of excitement. Your gear should make you want to listen to every track you own. You should be tearing through your music collection thinking "I've gotta hear this next, then this, then this". You should ache to get home and put on some tunes. It should be like the first flush of a new romance, but every day, every month, every year. It should be a love affair between you and the music. If the gear you own doesn't make you crazy in love then you haven't found the right gear yet. That's why you don't buy blind from a dealer.
All the five-star-reviews in the world won't give you this. There's something called synergy. You won't get synergy by cobbling together 5-star products. Synergy is more elusive. A good dealer - one who loves music and sells from the heart not the head - can guide you. They may put together bits of gear that you wouldn't have considered, and end up with a system that's more than the sum of its parts.
As for Sonos Vs Bluesound; I'd go Bluesound if you've got subs to high quality streaming services. Sonos is good (I'm a dealer for it), but it's mass market. Bluesound is aimed at music enthusiasts.
