Here is a review on the "RKA IN-Charge Shiloh Road Mini 3 point" tank bag.
Communications Main Page (Master Acessories Build Sheet)
The bag itself is well made. Three point mounting system is very stable. I can turn the handle bars lock to lock with no interference. The GPS is in a good location, and there is less vibration transferred through it. There is a handle on the bag which is a great spot to hang radios, heated gear controllers.
I didn't like the idea of a tan bag originally. I bought it because I was getting electrical interference through my Starcom1. No more interference, and the storage space is a bonus. I wish I had done this sooner.
Pros
Well constructed
Made in the USA ( for you Americans)
Very stable
Easily removable ( for security)
Designed for intercom and GPS no jury rigging
Cons
Expensive
Not water proof
Easily removable (for theft)
RKA Communication Tank Bag - a set on Flickr