After using my Gaoersi 617 for over 18 months I can tell you they are very robust, well finished & excellent build quality. I've also handled 2 or 3 Fotoman cameras and there's nothing really to distinguish between them in terms of quality etc..

The price difference is mainly due to the way they are sold, you currently buy Gaoersi's direct with no distributor adding a markup, as that changes I'd guess the price differential will narrow significantly.

I have the Universal view finder, it's OK, this is the one some people don't like but it's fine with my 75mm SA, but for longer lenses a dedicated finder for each focal length would almost certainly be better, if tha is going to be your main lens.