If you want to use Soft Lock on some of the harder missions in NYM then I say go for it. I did it myself and I have both NYM and NYM Hardcore completed. Took me 8 tries for NYM Hardcore just to give you an idea.
100% Completed: 226 | Total Games Played: 229
Current Percentage: 99.78%
Currently Working On:
Rayman 3: HD
On The Back Burner:
Ninja Gaiden II & Trials: Evolution