Hi Guy!
Here is a long answer (below) I gave when discussing the Viper Tec, which I believe is your Primary Reg for the HUB. My best advice is try it out first, if you have the chance. I really liked everything about the Viper Tec, until I actually used one diving! The HUB itself looks like a great idea, if you like the components. I saw one at a local shop after I had already got my reg, etc.
dmentia
I have several things that I had problems with, and they all added up to being disappointed in the reg.
1st, I felt the side exhaust did not clear the bubbles as well as it should have. It seemed to me that the exhaust valve was not "extended" to the side enough. Since I was also having problems with a mask that didn't fit well, the bubbles came up the side and "pushed" their way into the mask, causing some leaking. However, when I tilted my head just a bit the bubbles did clear without interference.
2nd, Even though the reg has a low profile, it did not sit well in my mouth. The hose I have is too short, but even when I used my Viper octo with a long hose, the reg seemed to "pull" at the corner of my mouth. I think this is also from the shape of the side exhaust.
3rd, The Viper tec is designed to push/send air into the mouth for ease of breathing. I had read that sometimes if you try to breath too hard, it "forces" air to the back of the throat. In the Viper Tec I have, this is true. My very first dive, I was having several little things go wrong at the surface, due to the mask leak and surface chop. I got a bit anxious, and tried to take a deeper breath when the air got shot to the back of my thoat. It was not comfortable. If I had not read about this tendency, I might have gotten with panicky. That said, this problem is supposed to have been fixed in the newest versions. If you purchase an older Tec, there is a spring that they can add to the airway to slow the force of the air down. So this concern may not even be valid anymore.
The last thing I can tell you, which I did NOT have happen to me, is there were some comments from people (at Rodale's
http://www.scubadiving.com on their equipment board) that the Viper Tec has a tendency to free flow. I don't know if that is true, since I never had any problem with that.
I think that if you get a chance to try the Viper Tec in the water, you may find that all of these are not an issue. The reg itself worked great down to 100 ft, and I never noticed any kind of performance issues once I calmed down and breathed normally. But the pulling at the mouth, and the bubbles under the corner of the mask when I looked straight down or forward make me want to try a diff reg. I will make sure I try it in the water this time!