Devon, the pack Ryan has been working on with HMG is pretty large. His personal pack is actually even larger than the model they plan to sell (I have one of the current protos). It's a bit more expedition sized.
With a smaller 2-3 day pack, a lot of people like them stripped down. Some add-ons might be a stretch mesh pocket for the front, water bottle pockets for the sides, or even expansion packs for when you can't quite get it all in the main pack. Those are just thoughts at this point.
With the HMG, I've made a stretch pocket for the front and huge hip belt pockets. I also may make water bottle pockets for the sides. In my case, the mesh pocket on the front will almost always be used in my home area. Whether I take one, two, or no hip pockets will vary by trip. In other areas I might switch the mesh pocket out for a solid fabric model. I like having one pocket I can vary the features on. Right now the HMG is my only pack. I hated having a ton of redundant gear lying around for specialized trips. I'd rather have a generic pack I can attach specialized pieces to. Of course, I may be completely alone in that line of thought.