unbleached flour vs ap flour

you should never use bleached flour for bread...or much else for that matter. All purpose flour is no means bleached into its all purpose category nor does the lack of bleaching make "bread" flour what it is. all purpose flour is ground from lower gluten spring wheat and possibly mixed with higher gluten winter wheat to get a flour that is good for general kitchen uses, biscuits, pie crust, bread ect. Bread flour has a higher gluten content and is less well suited to some more general purposes where a strong gluten network is not the goal. that being said you can make a great loaf from either and you could totally make a passable cake or pie crust from either as well. bleaching is an artificial aging process used by companies willing to sacrifice the integrity of their product for higher output.

edit: woops, I just reread yer post and noticed that you said unbleached flour and ap, when i first read it i saw or, my bad, I think if possible you should pick up a nice five pound of king arthur bread flour and some who grain flours of your choice in small amounts from a bulk bin would be best and experiment with adding smaller percentages of lower grain flour to a nice strong flour that will be hard to accidentally weaken enough that you might have a hard time with it.

edit #2: upon reading your post again it occured to me that possibly you were simply asking if mixing ap and bf would hurt or help. I almost always mix some ap into my bf, just to cut down on the toughness, an example of when I would stick to just straight strong bread flour is if I wanted to maintain an open crumb but I was using higher percentages of whole grains or whole grain flours, especially if those whole grain flours were milled from things that would contribute little or no gluten to the mix.