I have never seen Kurz's work but have understood it to be very effective. I will try to pickup his material and give you a more specific opinion. I love flexibility work even though I don't see any reason to be able to do a split. Again, I love all things in balance. Good for you, taking the time off training. It's a hard thing to do for some people. I think you can get bigger and keep up with your flexibility and cardio, too. I always think it's a good idea to mix things up. A maintainance program that will help you hold onto your added size will be a more substantial program than the average Joe's maintainance. Your nutrition will help you there a lot. If you add some good lean calories during your building phase you will see results much faster. The general recommendation is around 500 new calories per day. A great way to do this is with protein shakes spread out between meals. One of the best times for a shake is right after your workout. If you time your workout a couple of hours after a meal then your body can use up the calories and there is some evidence that you have greater amino acid assimilation immediately after a heavy training.
Thx for keeping us posted and I will watch for your pm.