I'm an advocate of do what you want. With that said here is what I do. Not trying to convert you but you asked about living books and I use them so here goes.
We do use living books here. There are so many wonderful picture books for science which I consider to be "living books". I am a book addict and my 2nd grader is my 2nd child so for years I have been book scouting at library sales and such and already have many living science books on hand.
My children also do outside classes with science, Audubon hands on classes and some other programs. They get so much hands on nature at those classes that my own nature study with just me with them has decreased.
We are not big on science experiments here. I do have books with experiments laid out. I own kits already. But I am being honest when I say we don't use all that we have on hand.
A book I also like which I bought years ago at RRC is unit study based using picture books as the jumping off point. It is like FIAR but for just science topics. THe books are by Carol Butzow. Science Through Children's Literature. You don't need it per se but I'm mentioning it in case anyone feels worried about covering a topic thoroughly when using picture books as the content material. (Butzow writes other books on other topics which are based on real books too.)
I also use Science Scope by Kathryn Stout as a check list of sorts to see if all we read with the picture books is "enough". Mostly I use it when I'm worried or feeling insecure, which is not so much right now but I did when I was using living books just for my older son.
Unfortunately my kids have been bored by the nonfiction centered Burgess books.
Some friends of mine love the Apologia books for elementary. For me, I feel like I own enough already, that for me to buy that and use it would be overkill.
Do what works. Enjoy it.