I'm following The Simple Diet from the book by Anderson and Gustafson, and most Ideal Protein products fall within TSD, so I've been scouring the IP and Medifast threads, especially the alternatives and substitution threads.
This thread has been very helpful. I've studied the nutrition labels of many of the name brand and grocery store products, and I'm not convinced that any are as carefully balanced as the makers claim, at least for plans that allow you to pick and choose your options.
I have a decent nutrition and research analysis background and to me, it appears that the calorie, fat, protein, and carb content is as far as balancing efforts go, so its perfectly safe to choose alternatives that are matched on these nutrients as long as you're eating plenty of low-cal vegetables in an assortment of colors (which you need to be doing on the name brand foods too). Taking a daily multivitamin wouldn't hurt.