If you go shorter stem, you have to go wider bars to compensate. The bonus is the handling is significantly improved. Personally, I would go in the range of 35-50mm stem and somewhere around 785-800mm bars. Deity bars have a very nice backsweep to put you in a more natural position. I know you are 5’9″, but one of the best riders I know is also 5’9″ and rides a 35mm stem with 800mm bars. (http://www.dirtsmartmtb.com) If you are hesitant, a shorter stem and sliding the seat forward will be quick fixes.
As far as the bike being “too much”, that’s actually a good thing. If you have a bike that is “just enough”, as soon as your skills get better or you get on a more advanced trail, you will hit the limitations of your bike real quick. You want to grow into the capabilities of your bike, not have to keep upgrading bikes to fit your capabilities.