from B&w 805's to Usher be-718 - what to expect?

I've heard both of these speakers and would say they produce a very 'colored' un-natural sound. I suggest you hear some single driver speakers to put balance in your evaluation before making an switch.

Big downgrade.

The 718 are highly overrated.

I had a pair here for a couple weeks; drove them with a pair of highly regarded Class A solid state amps as well as Class D amps.

Chalk on a chalkboard. Much too analytical and clinical for my ears.

Stay with the 805; they are the lesser of 2 evils.

IMO

I too liked my old 805's better than the Tiny Dancer. I thought they were better in every way. Maybe an audition first. Listen to them both side by side.

Do you have a friend or dealer with a broken in pair?
These take a couple of hundred hours to fully break in.
Until they do, they sound exactly like their detractors say they do.
I do have a bias. I own 2 pair & the matching center.
This is the first tweeter to sound better, to me, than my Avalon Avatars.
And my Avalons equal or better any comparable size B&W speaker I've heard.
These speakers are truly revealing. They remind me of my Magnepan 3.3Rs, any improvement in equipment upstream of the speaker is rewarded.
Why don't you audition a pair (if possible in your system for an extended time) and then post a thread on your results.
Your opinion is the only one that matters. Our input is valid in our systems, with our room acoustics, and our taste.

I agree with DanielK141. Audition them and see how you like them.