Just out of interest.

Think it might be snake oil me'self but I've never ridden one so can't say ... anyone ride it/tried it?

I'd have to agree.

Although I have heard some very convincing arguements for them over the past week.

Until I ride one, I am convinced they are marketing hype. 29ers FTW (see I'm so down with the kids).

I've ridden one (a riding buddies). a full suspension scott genius. It was a great bike.

However, My bike that day was a 26" wheeled nicolai with 2.4 tyres. The scott had 2.1 tyres and the overall difference was incredibly small.
I'm sure it'll catch on, mainly cos of the investment and the 'something new' factor but I really couldnt tell the difference on the trail.

Not ridden one but experimentation can only be good.The problem as I see it though is it comes too quickly after 29ers which are only just becoming mainstream in this country. Will people be prepared to buy into a new wheel size so soon after 29ers because it's not like just changing a component , as well as the wheels you need a frame designed for them, tyres and probably a suspension fork. Rigid 29ers suite bike packing well but the 650b may well replace 26ers completely.

Purely from the "standing them next to each other" test 29ers seem worth the hassle as they are noticeably different. Being 700c also means there is a wide range of bits that can easily be pressed into use as spares. 650b is different enough that it "won't" play nicely but not different enough to make a tangible difference in ride (guessing I've not tried one). All IMHO of course!

I suspect it is a diminishing return. I Have not ridden one. I don't really mind / care, it's all bikes.

Anecdotal stuff indicates lots of the bigger manufacturers are geared up with components for 650B, more so than they did when 29 started. This might be because the changes from 26 to 29 are not so great (easier and cheaper to achieve than it was for 29) and also might have something to do with the fact that they've already gone through the cycle of "a new wheel size" and so are not as shy of it as before.

I do think a huge amount of it is hype and marketing to sell more bikes and in the ever harder search to convince the punters each brand / bike is something with a really special USP.

I wonder what'll happen to smaller or even mid-sized bike shops. AFAIK most struggled to stock a range of the models and sizes from one or two manufacturers, how are they going to manage when you throw in different wheel sizes, and then the corresponding components, all the wheel size and standard variables, never mind tyres.

Not necessarily a reason to avoid change but it could be a challenge. I like LBS's but unless you're getting "mates rates" or big discounts then I still shop for most gear via the internet or classifieds.

Having made the leap to 29er and liking it Im not going back down a wheel size. 29er is my new standard (for me)
Having said that the kids need new bikes next year, so will step them up to 26''. Im hoping the market will crash in this wheel size, and there will be much cheapness about (Before anyone says ... yes that appeals to my Scottish heritage )

For my next bike, Im seriously considering a Krampus for Bikepacking duties. The 29+ 3'' wheels should roll nicely