One of my barn-mates has an Aviar and loves it. Depending on the seat size you need it may work great. Like Customs (I think they are a sister company of Custom) they have some “non-weight bearing” panel extension out the back that made my shorter backed (long loin) guy very uncomfortable when he lifted his back. My guy is going ok in an Amerigo but we went through needing fitters out every 3 months or so after I injected his SI and rehabbed him. The topline changed immensely so having wool flock during that time was helpful. I will also say I had my fitter adjust the saddle to accommodate a memory foam half pad to give his back some room to build that muscle. Still needed to adjust flocking to adjust any rocking but that seems to be working for us so far!
While the Aviar panels are changeable, you may want to inquire about the process. Is it on-site/immediate? My friend who has a CWD can also change the panels on her saddle, but she has to send it to SC (I think) to get that done. Likely 4-6 weeks without a saddle… Just something to keep in mind.