Welcome to the EGGhead Forum - a great place to visit and packed with tips and EGGspert advice! You can also join the conversation and get more information and amazing recipes by following Big Green Egg at:
like others have said, best thing to do with lump is try a few and use the one that you enjoy the best.....there are differences you will notice as you cook and as you eat.
as for the digi-q, I have one and it works as advertised and it does the job. however, I have become more of a hot and fast kind of cook and it pretty reduces the need for a controller, because I am usually around the egg while I am cooking.
I would only get one of these controllers if you plan to cook overnight on a regular basis at a low temp, or as someone else pointed out, if you are going to be involved in cooks where there are lots of things you are responsible for taking your attention away from the egg for long periods of time.