I've started riding more technical stuff and found my narrow XC bars a bit too low and narrow even with bar ends. The geometry was very much long and low at the front and arse up at the back. I experimented various setups, firstly a higher stem, which changed the feel dramatically. It made me more confident on descents, but the stem was shorter than before, which made the bike even more twitchy, and bizarrely, as speed increased, so it felt that I was having to wrestle the bike a bit more. Eventually I put a pair of 720mm lowish riser bars on, and now love the setup. The only downside is seated climbing, where I now have to scoot forward on the saddle to keep the front wheel planted
So, to answer your question from my experience, you need to find the stem/reach/width that sits you up a bit more that the race position. Shorter stem will be more direct in terms of steering, and a wider pair of bars will calm it all down a bit.