David, if you do a ton of narrow component sanding, then yes, the smaller 125mm/5" format is going to be easier to keep things flat. But in general, the current generation 150/5 (or similar from Mirka, etc) is, in my opinion (cheap for sure), one of the best overall sanders one can own. Until I recently bought an RO90 for some specialized reasons, I've been using the 150mm/6" format since the mid 2000s and have never had any real issue during those times when I was sanding narrower things. I just am careful. My original sander is the 150/3...the taller design from "back in the day". I picked up a 150/5 in the current, lower format and I love it. There isn't enough difference between the 3mm orbit and the 5mm orbit to matter to me, at least for the work I do.

I do not suggest you buy a Rotex to use as a general sander. These are two-handed tools, IMHO, even in the current slightly more balanced format, so doing a lot of general sanding is going to be more tedious with them. Buy a Rotex for the aggressive, rotary action if you need that and for that. Buy a ROS for general sanding. And this comment is not brand specific, in a sense, because other brand options for dual mode can be equally discomforting because it takes more "stuff" and space to do the dual function and that raises the weight as well as the handling issues. That's my opinion, of course, and again, it may not represent yours or other folks'.