I would think the biggest reason NOT to switch brands from the others, is the control. For example, my control is Dometic and one single stat controls the group of four. Switching brands could pose compatibility issues if just changing one RTU. If each RTU had it's own stat, the result might be different.
We have had some issues with our Dometic. Had a guy in PHX work on it to no avail. (long story) We ended up going to Newell where they replaced the compressor. They have found some replacement parts sources. I would recommend repair if possible before complete replacement if possible. If you do have someone work on it make sure they read the attached material. It would have saved us north of 1,500 if the guy would have read before working.