I’ve owned a couple of the special project 4x’s on and off for the last 5 years and they are mint bikes, really really mint. I sold one and then instantly regretted it and so bought another.
As a messing about in the woods bike or hooning down smoothish decents they can’t be bettered, I’ve even raced DH on it and it was me that was crap, not the bike. I’ve had a blur 4x and although it had more of an alround appeal and made more sense with it’s extra travel and room for a front mech and longer seat-post, it just didn’t do it for me in the fun department compared to the yeti.
I do have the advantage of only being 5’6 and so taking the yeti to the trail centre or on an xc loop for a couple of hours is possible, when i’m fit that is. However, with a young family and competing interets, “messing about in the woods” never happens and instead what i really ride nowerdays is xc with mates. I have therefore just bought myself an xc bike which gets most use.
I reckon at 6’1 if you can get a 4x in the long size, run it with a 70mm stem and put up with climbing out of the saddle you’ll be fine. Just be mindful that if what you ride most of the time is xc orientated, with long seated climbs then you might be better off with the ASR5.
just my 2p worth