Sonar went through a MAJOR and complete UI redesign, and is not likely to ever go back, or offer any way to maintain 8.5.3 UI functionality.
Many many folks bitterly complained about the redesign of X1, but have come to embrace what are some significant work flow improvements.
X3 has some really wonderful features, and if you take some time to invest in learning the new ways of doing things, you may come to like it - as many of those who had originally complained have done.
There are lots of videos, some well-written (and current through the release that just came out today) books, and of course the forum.
Why not download the 30-day free trial and give it a good test drive?
Bob Bone