I´m in a similar situation after a test ride of an Orange Stage 6 Evo (150/140 travel) a friend put me on after I complained that the trails here are quite sketchy to ride on my current "modern" bike, a 2013 Santa Cruz Superlight (120/100 travel). While the bike´s travel and geometry certainly also made a difference, it was clear that the wheel size (29", 2.4) was most noticable for me. The level of grip and the ability to roll over much more stuff than the 26er were quite a revelation. Trails where I jackhammered before with clenched teeth were suddenly enjoyable.
I can only echo what benjabbi said: test ride before you decide. And I mean not only bikes you´d consider purchasing, but really anything modern (long reach, short stem, slack head angle, steep seat angle) to get a feel for what you really want/need. I mean (up to) 5k is a not insignificant purchase, so I´d want to make sure that what I get is exactly what I want. I thought before the Orange would be a slug with nearly 15kg, except it wasn´t that big of a deal. The question for me right now is if I really need 140mm travel in the rear. Trails around where I live are not that demanding so to really use such a bike I have to load it in the car and drive 30-50km. OTOH, that ´s what I do with the Santa Cruz also. Around my house I prefer to ride my retro bikes.
Lastly, bikes I am considering are mostly british and single pivot (I found linkage suspension to feel a bit unnatural):
Starling Murmur
Cotic FlareMax or Jeht
Orange Stage Evo or Stage 6 Evo
Marino (from Peru)