SH engines are a manufacturer out of China. They are value oriented. Depending who you talk to, they are either cheap crap or easy to tune and durable. I think Dynamite, Losi, SH, Exceed and many other brands are made from the same designs, with little significant changes to differentiate between them. I run them because that's what came in my ready to run cars.
You can learn and not have to worry about hurting a $300 engine if you don't get it right.