I been using ninja for the past 3 month. To me, it look like a software in version 0.3, not 6.5.
Many things are missing. You cannot remove spike in a chart, unbelievable.
I will probably switch soon but is there a better solution, I don't know.
I found better, Dow 40,000! You can buy many copies at 0,01$, good deal.
http://www.amazon.com/Dow-40-000-Strategies-Profiting/dp/0071351280/ref=pd_sim_b_3
I just switch to DTN IQfeed. 120$ per month with cbot and cme. Its MUCH faster that IB. Before when I was changing instrument, it could take 20 sec to load with IB and sometime it was hanging and I had to restart ninjatrader. Now it take under 2 sec.
Also continuous contract are much better...
I use ninja trader. Its good to me and I feel it will improve with time.
For backfill, I try DTN for a 1 week trial and I will probably go back to them. IB is slow and I can't stand the fact that they don't have continuous contracts.