Fermentation with a single, aggressive, "domesticated" strain is fast and effective. That being said, I don't personally favor it when it comes to fruit brandy. Wild fermentation, if done properly, can allow a more subtle, nuanced profile that expresses the fruit without the influences most people describe as "Strong-liquor" like.
To make a predictable wild ferment, take a small amount of the unwashed fruit and prepare a starter by putting it in an anerobic space with allowance for gas to escape - this could be something as simple as a small bottle or ziplock bag with a small corner just slightly open -- then add more of the fruit you are going to eventually ferment to keep the starter alive. Once it is a large, healthy starter, mash the rest of your fruit and pitch the starter into it.
The caveat is that as with any wild ferment, there is a risk that they do not attenuate as well or will produce polysaccharides as a response to the rising alcohol content, thus lowering yields. Keeping the potential alcohol low will prevent this from occuring.
In terms of actual distillation, both apple and pear are distilled on "Light lees" in Calvados country. To make a judgement on what amount to keep within the ferment/still, think of it in terms of Grappa versus brandy - One is very woody tasting, the other light and fragrant. Apple peels have a unique taste, if you chew on them alone. If you distill with all of the lees and mash in, you'll certainly have more influence from the skin and seed. If you distill with a small amount of the lees in - about a quarter of the original leftover apple pulp/skins/etc, and press the juice of the rest, you'll have a more balanced profile that features all aspects of the apple. Either way, I don't agree with distilling completely clarified juice with no pulp. It simply won't produce the same profile.
For pear, personally, I actually like to keep the entire mashed pears, fermented fully, within the still, without removing anything. The pear's skin is much more subtle in taste and adds a pleasant countryside (can't think of another term) sort of aspect that is difficult to obtain without it.