The further away they are from the MOSFET, the longer it takes for the thermal feedback loop to operate. (Bob Cordell has a picture of the speed with which a diode reacts to BJT temperature in "Designing Audio Power Amplifiers") Operating in Class A, this may be less important.boyz , you're splittin' da hair
put them where you want , as long they're firm in place , with steady and good thermal contact with mosfet's case
The leads shown from the 6-Moons article are quite short (a good thing) and the temperature sensing device won't move. I wasn't as careful when i did my PCB's and find that the devices weren't in the "intimate" contact I had when first established.