GX35 vs 139-F2

I have found a supplier of single engines at a very good price in China. They have the Honda badged GX35 copy, and another 4 stroke, the 139-F2. Does anybody have any experience with either of them?

The GX is ohc, the rating given by the maker is 1kw/7,000rpm against the 139 at 0.7kw/6,500. Looks like the GX is a better option, and also from the point of view of spares here if needed.

And now, after a trawl through pics etc, it seems the 139 is a GX31 copy. I'm rather fond of single cam pushrod motors though, "old fashioned" they may be, but they have advantages. One is that if the 139 cam gear wears, it can be replaced easily. Another is the less convoluted load paths of the respective ohc and ohv rockers. The 35 takes the drive through 90 deg along short shafts from a high set camshaft; calling it ohc is a misnomer. I do not know if the cam runs in a plain head, a bush in the head, or proper rollers. Added to this, the 35 uses a "lifetime" cam belt. Having known several people with dead car angines from prematurely failed cam belts, I doubt it.

And $20 cheaper for the 139. Hmmm....