I was hoping for someone to respond using their experience and opinion on why their views differ from mine. While i have brewed a few times with pumps, baskets and automated systems I haven't ever owned any of these items. Ill outline my views of each of these items, if anyone wants they can respond on each specific item on how their view may differ.
Basket with bag inside:
this method offers more support for the bag but also has a higher chance of dry firing under the basket. To prevent this, I think its important to modify the basket to have as many holes in it as possible to allow for free flow of the liquid. the basket also changes the drainage characteristics. The bag when hanging tends to "self squeeze". the basket holds the form and doesnt squeeze the grain as much. Is this a useful characteristic to allow for rinsing of the grain while it hangs in the basket? Do people squeeze the grain afterwards, or in a different way?
Just mesh basket:
This is similar to above but instead of using the lining of a bag, they use metal screen mesh for the basket lining. Mesh will last longer but depending on the screen gauge may allow grain to get stuck in the mesh. I think the functionality is the same as above.
Just bag:
Just a bag is the cheapest option. It seems to me that the bag doesnt impede temp transfer throughout the kettle as much as the metal basket, but the bag may block the inlet if u want to use a pump to continually recirculate. I personally havent ever had a bag burn, but i dont turn on elements while mashing unless i raise the bag. One drawback is even the strongest bags tend to wear out quite quickly when grain bills excede 25 lbs.
Channeling:
When using a mashtun(tradional batch or fly sparging), channeling is quite a large issue due to a low water to grain ratio. The mash tends to be thick like porridge and making sure the hot water contacts the grain is more important. With BIAB the water to grain ratio is super high which makes the mash more of a soup then a thick porridge. As long as their is no dough balls and mash temp is correct, complete conversion is basically guaranteed.(I have heard it only actually takes like 10-15 min for full conversion in biab)
final result:
I like to reuse yeast and biab tends to leave alot of matter in the prefermented wort. While it seems that this extra material is useful for fermentation, i prefer to remove as much of it as i can to maximize my 6gal fermenter and keep the bottom yeast as clean as possible for reuse.
After mashing is complete, does anyone pull the bag/basket and recirculate into the basket to filter the wort?