I don't have a MixPre and frankly, the present discussion would tend to make me think twice about getting one since I mostly use rather high-output condenser microphones. But I feel that something essential is being left out of this discussion: The pad switch on most condenser microphones makes their signals (in effect) noisier by the same amount as it reduces their output level. So the use of that switch is almost always a last resort.
The one time the pad switch on a microphone MUST be used is when the sounds are so loud that the microphone's own internal electronics are being overloaded, or are likely to be. In that case, nothing else will help and the microphone's own pad switch must be used.
But if the microphone itself is doing fine and the problem is that its output is overloading the input of the preamp or recorder that it's connected to, the thing to do then is use a resistive pad at the input of the preamp or recorder--not the microphone's pad switch.
This isn't a question of ideology or opinion. Every microphone--and BTW, this includes microphones that don't have any internal active circuitry, such as ribbons and other dynamic microphones--has some amount of noise in its output. Some is generated within the transducer, and then if active electronics are also a part of the mike (as in condenser microphones), some is generated in the active electronics as well. The pad switch on most condenser microphones is placed at the input to the active electronics of the microphone. Thus it reduces the microphone's sensitivity while (unfortunately) not affecting the noise caused by the active electronics (which generally predominates at higher frequencies where it's more readily audible). Voila, the signal-to-noise ratio is reduced by 10, 12, 15 dB or whatever else the amount of the pad is.
A resistive pad at the input of the preamp or recorder, on the other hand, knocks down the level of both the microphone's noise and its useful signal by the same amount at the same time--it can't tell the difference, obviously. So that approach is preferable by far, and hugely outweighs the inconvenience of bringing a couple of in-line pads along to the recording.
--best regards