I can't comment on the difference between the two 2x15 styles and their sound, but I have experience with the 2x15 w/port in the middle, and also a custom 1x15 I had made which is very similar to the Sunn 1x15, but just slightly bigger. The 1x15 sounds just as good as the 2x15, but of course it is more portable, and not as loud. It still does the bottom end response quite well. I just used the new cabinet last night at a blues jam gig with a 200S head and it was GREAT for all the basses that were used in it including an upright. I don't currently have a 2x15, but I remember the sound of the one I had well and think they are great. I think either way is a good approach, and I would base your decision on portability and how often you think you'll need the power of the 2x15.