Actually the final battle was by far the most challenging combat I've encountered in solo missions which includes feature content and foundry content. Normally I'll waltz right through without breaking a sweat in my assault cruiser (It is well specced for soloing against large groups) but I was in great peril in the final combat. It was refreshing and a thrill to be really pushed to the limit like that. Also please note that I did it on Normal difficulty. If I did it on Elite...I would not have survived. So basically what I'm saying is that the difficulty level was fine. Do not change it! It was a great thrill.