You'll get exponentially more opinions on braking systems than there are manufacturers thereof.
We have an SMI Air Force One, wonderful for DP coaches having air brakes. Extremely well balanced with proportional braking. We tow a 2012 GMC Acadia - never a problem, and we travel Wolf Creek Pass in Colorado frequently. That will certainly test any braking system.
All the best in your decision, and congrats on the new coach! My son has a Mini Cooper - and I'm envious.
Joe and Debbie, Emma the Aussie Cattle Dog who adopted us
2012 Discovery 36J, Blue Ox and Air Force One, 2010 GMC Acadia Toad
USAF (Ret) WDØM http://wd0m.com