No experience but it's a Korean company. Korea is not a low cost country and quality is usually good. I checked their website (I know a website is a marekting instrument) and if the history facts were true, I would not have reserves.
If you have serious doubts, I'd suggest that you contact them with your enquiry, with the specific request that they first furnish you a list of references, who you can talk to.
I work for a valve manufacturer and we sell valves with Sambo gears on them. I have not experienced any difficulties with them and find that they are a good quality product.
Attached is some info that I had on Sambo gears...not sure how old it is, but it might be of some help to you.
We used to use thier bevel gears and they also used to do some machining for us several years ago. I visited the Sambo facility for a brief tour back in 2002 nicely run shop but a seemed a bit dis-organized (it was split like in 3 separate buildings over a couple blocks). They did very good work for us and we never had quality problems. Only reason we pulled out is because we opened our own facility in China
I have tested large multi-turn Sambo gear boxes on globe and gate valves. Typically, Sambo mechanical advantages are attractive (better than most manufacturers) and their design is very robust.
In my experience,Sambo does manufacture good quality gearboxes. I would not say, in these days, that Korean companies are low cost manufacturers. This would depend on each of our standards.