You can definite make persistent audio interface settings. The preferred way is to set them in your patch.
Preferred by whom ?
I can't picture anyone wanting to set anyone else's audio settings when they send someone else a patch.
I guess you don't work in anything but 44100 sampling rates. I have done projects that use 22050 and 48k, and both won't work right unless the sampling rate is set correctly. Therefore its an essential property of the patch.
But you can often use [samplerate~] in those situations no?
There are some times when you have to know the sample rate beforehand, especially in delay situations where an algorithm depends both on the milliseconds of delay AND the actual number of samples. This can happen in reverb and filter design, and elsewhere. Otherwise this is also a problem in more obvious ways when you're playing sound files -- sometimes I'll make my patches so that if it detects the wrong [samplerate~] it tells the user to close the patch and fix it.
Which reminds me: there used to be a problem with [delwrite~] where it would allocate its memory when the patch containing it loaded, based on the sample rate active at the time, such that if you switched Pd to a higher sample rate after the patch loaded, you'd have the same maximum number of samples of delay, but not the same maximum milliseconds. I remember there had been talk about fixing this, but if it's still a problem, this might be a reason not to set sample rate from the patch.
Matt