I disagree that the mechanics are the same. Thermocouple thermometers are quicker -- much quicker -- than thermistor therms. Thermistor therms require 1/8-inch probes (at least) and are not 'instant', as Doug notes. They usually take 20 seconds or more to hit temp. You can check how long yours takes by turning it on, letting it hit room temp, then immersing in a cup of ice water and clocking how long it takes to hit 32. Then you'll know how long you need to wait at least when checking meat.
Most thermistor therms require insertion of at least slightly over 1/2-inch to be accurate so keep that in mind.
Thermocouple therms can use much thinner probes and need only 1/4-inch insertion. They can it temp in less than 4 seconds. That's what you pay for.
Thermistors can certainly be just fine. Just know the time necessary to hit temp, make sure insertion depth is sufficient, and be careful of the point where the probe in connected to the readout, and of the readout itself. Many don't handle moisture well in those spots and quickly 'fry'.
