Went to my appointment at U of M Medical Center and was seen by 2 Physical Therapists - expert in seating issues, and a Physiatrist. A very in-depth interview was done thoroughly covering my seating history, what cushions I have used, how long, discomfort areas on my bottom, home layout, home responsibilities, basic activities of daily living, wheelchairs used, manual and power, etc. My husband was present and explained the cushion he fabricated for me by combining a modified foam base under a standard cushion, in addition to remembering the names of all the cushions I have used.

I was then "pressure mapped" - lifted up while in my wheelchair and that piece of wire-grid-embedded cloth placed under me. That device is connected to a small computer-type screen, and sure enough a red spot right where I was hurting. (I am not SCI, but paralyzed and retain sensation). Time was spent adjusting my position, with the specialists going over the display screen.
In the room there was practically a wall of shelves full of various wheelchair cushions, and we discussed my experience with several models I have used over the past 20 years. None of the ones I have used in the past were comfortable for more than about 3 months, after which I would switch to another old one or order a new one.

A physiatrist then came in and did an assessment, checking the structure of my hips, posture, the screen of the pressure map, etc. I have scoliosis and thus my seating profile is not symmetrical like a person with SCI might likely be. Most of the pressure is on only one side.

A couple of newer type cushions were discussed and one taken from the shelf. That model was too large for my wheelchair width, but they demonstrated how the user could use the handy buttons to deflate the cushion, which is fully inflated when one is not sitting in it. Once in it, the buttons allow you to deflate it to your comfort level. A Ride Design Custom was also discussed. As this cushion is mainly used for symmetrical bottoms, I was shown an insert that might be used in my situation.

The Physical Therapists will call vendors to get loaner cushions in my wheelchair seat size and I will meet with them again in the next couple of weeks.
Both my husband (he's SCI), and I were totally impressed with this very in-depth evaluation of close to 3 hours.

My husband expressed concern that more wheelchair users could benefit from this service - we were told that it's tough to get Medicare insurance approval for custom cushions, due to the various coding requirements. Apparently all of the many history questions they asked me relate to meeting the wheelchair cushion codes.
The importance of appropriate wheelchair seating is tied to the cost of pressure-sore rehabilitation which can cost in the thousands of dollars, when a proper cushion would be a pittance in comparison.