The 536 is the same size as the 996XT. When I migrated from the 996XT to the 536, all I had to do was unbolt the scanner and disconnect the cables. Then stuck the new one there and re-connected the cables - the cables are the same for both scanners.
The 536 decodes simulcast systems a whole lot better than the 996XT did and I really like that I can "re-program" the scanner by popping out the SD card and taking it to my computer. With the 996XT, I had to take a laptop to the vehicle, connect the cables, start the vehicle and leave it running for however long it to the revised program to load.
The only present "beef" I have is no remote head capabilities, but I've got faith that will be resolved before too much longer.