you can pretty much use any MTB for off road touring
it really depends on "how" you tour

personally I've been into the BikePacking method.
racks, panniers, etc... its a whole lot of stuff to carry, and if you ride a ton, there is a good chance that something will break
I mean to say...
that racks and panniers typically have some kind of slapping around that goes on in between the pannier and rack
so hot spots develop
and welds are prone to break.

ok...
ok...
ok...
ya right

I also have used my Pug for a ton of touring and it has racks and bags... never broke a rack
nor have i broken an Old Man Mountain Rack

but really...
In comparison to using frame bags...
and simply reducing your gear...

its a much better option.

when it comes to touring, the route, provisions, resources, etc...
its infinitely variable

I'd say, if you have touring experience
and if you have MTB experience
try your best to morph in the direction of MTB -> Touring
vs
Touring -> MTB


my current setup is a custom Hunter 29er that pretty much does everything
it has braze ons for racks, fenders, et al

But its the best with just frame bags.

the method with racks, leads to large baggage
most of the time, if you have the luggage, you will fill it

the question becomes what comfort do you want?
comfort in camp?
comfort on the bike?

I've done some touring on the cheap where I am literally living On The Road, lots of rain, little to no money, etc...
so I'd carry a 4 man tipi complete with wood burning stove.

The Big Dummy is more than capable to haul, even fire wood and an axe...

however, I will say that I really do like a 29er!

depends on your finance...

I'd consider a Surly Karate Monkey
a Salsa El Maraichi Ti
a Dos Niner

uhh... a Niner Carbon Air?!

the list is just about infinite...