I have a Subaru OBW sitting in the garage and a tiller out in the shed with a Robin EX engine. No way would I rate the Robins and especially the small EX engine under a Honda. The EX doesn't have any plastic internal parts except maybe the chain tensioner. This is a OHC design and the crank is supported by ball bearings on both ends. Very little mech noise. Engines are warranted for 5 yrs even in commercial use. You think makers of equipment intended for commercial use would pick a 2nd or 3rd tier engine for this kind of application?
As for brushes Vs brushless, I'll take the brush design. On a brushless design there is a sizable capacitor mounted on the armature. I don't need something like that rotating at 3600 rpm and decides to come flying off. Not all that unusual for lower qlty brushless designs. If this happens it's not a DIY fix. You typ see brushless designs on low end intermittent use gensets. Not say ALL brushless design aren't decent but the majority small gensets aren't intended for extended use. Like the brushes on an automotive alt, on generators they're not a issue and last for a very long time. Need replacing, typ can be changed in a few min.
The genset in my MH, an Onan uses brushes and they are designed for extended use. Oh, that genny turns 1800 rpm. Also have a high end Honda. A model you don't see too many of. It also is a brush design. Speed regulation is great, I've measured freq at low and high loads and freq is held to +/- .5Hz. The engine on this genny is also not your typ design. 2 cyl OHC water cooled. List price ~$4k for 6.5kW. Now out of productions. Not sure of the engine specifics but would suspect it is top notch.
