I also generally agree with Brian's comments. To my eye, there is not a huge difference between MGIV and MGWT, although a side by side comparison does show subtle variations, especially when used with neutral, warm, or cool tone developers.
I have been using the ID-78 formula that Ian Grant published here, adding KBr and shorter development when I want warm tones and benzotriazole and longer development for cool tones. This seems to enhance the warmth or coolness of the finished print, especially after toning in selenium. And it is more economical than stocking 3 different developers.