http://www.specialized.com/bc/SBCEqS...jsp?ssid=Tubes

would a nice boy like pablo battani steer you wrong?

i just recently discombobulated a spec nipple neck for several miles-
like 75-without streessing the rubber.

the specs are weight and carcass comparisons not price.
A TT is in a completely different and sportier class than a Marathon.
While a Marathon or Pasela or? commutes, the TT is GT, it's a
forgiving life saving tire made commute reliable with a thicker tube.
The Marathon/Messenger class are reliable but a hassle for directional
control or stability: A loser over quickly varying surfaces: tar sand
tar sand tar on the shoulder next to traffic. That fact leads to using
a sport tire such as a Conti TT/thornproof on the front

Tire liners allow slime to work correctly with a very close mating
surface the inner side of the tire's contac area cannot give. Fluid
flow presses outward from it's hole, sealing and preventing air
release.
Liners are destructive from overlap and side edge pressures on the
tube so periodic maybe 3-400 mile tube checks at hi pressures are
necessary avoiding unpleasant surprises. Good for touring or a Tour
singular.