We very briefly touched on this, but you are right...there are several things to take into consideration (and not all physiological either) when setting up the most optimal diet for someone.
There are some things just within our own bodies that sort of "point" to the right direction for us. For instance, there is a fairly strong correlation between the "endo" phenotype and those particular people having better mood and energy on low carb/ketogenic diets - obvisouly because of the role insulin is playing within their bodies. That, to me, is an obvious sign right there. There needs to be a low carb/ketogenic approach to their dieting methods for cutting/maintaining/bulking. Cutting would involve more refeeds (think CKD, TKD, etc...), maintaining and bulking might be something more along the lines of low carb or iso-caloric. The point being, that you would NOT put someone like this on moderate to high carb approach. They will feel like crap all the time, their energy levels will be a roller coaster with lots of crashes, and they will ultimately just end up quitting.
Take me for instance. I'm extremely insulin sensitive (obvisouly if you've seen my journal and saw how high my carbs were even 1 week out from contest). But, in years past I tried the low carb approach. I was downright miserable. Now? I'm a little lethargic at times just from low calories, but I have excellent mood and energy most of the time. That tells me I'm using the more optimal approach for my body. Incidentally, my body before was telling me to stop the low carb approach LOL
There is more than one way to skin a cat. With some trial and error, paying attention to your body, and some basic common sense, you'll be able to quickly see what route to start with (and then tweak beyond that) to make things optimal for you and whatever your goals are.
Hope this helps...
Sporto