My friend (wheresjerry) has an NT4, and it pulls some pretty good tapes... but there are all ambient concert recordings, not close-micing. So it's a good mic an general, but I'm not sure about your particular application.
The NT-4 is arguably better for close micing than distant stuff.
Here are the catches...
Con: The fixed 90 degree coincident pattern can be a limiting factor on occasion,
Pro: The convenience of the fixed pattern in one mic makes it quick to set up.
Con: It's heavy and you can have trouble finding suspensions etc to hold it firmly. I have the official Rode C3 mount with the rubber-bands and it droops a bit in that.
Pro: It's built like a tank
Pro: It's excellent for close micing acoustic instruments including guitars, piano, ensembles (near micing?
and foley etc...I also use the NT-4 occasionally on ambient/nature work as it is quiet.
Con: I find the stereo imaging a little narrow at times (Y config is better for that), depends on what you are recording.
Pro: Has internal 9V battery that lasts for ages...no need for 48V phantom...although you can run it on that too if you have it and get some more
headroom.
Neutral: I have a Sound Devices MixPre and they are a match made in heaven.
Alternative: You have the option of a pair of NT5s, same capsules, in single pencil bodies.
Summary: If you can't get a good recording out of an NT4 then you should give up. A stereo pair offers more flexibility
Here's an idea: Buy a pair of Behringer C2 stereo mics ($80), some with stereo-bar, mounts etc...totally amazing kit for the money. Then you can experiment with a stereo pair on the cheap and decide if you want to upgrade. I have a pair of these for dangerous assignments...like putting in plastic bags and dangling them into the sea...etc. I think everyone should have a pair in their cabinet
NT4 Demos...
Close mic steel acoustic...
http://www.rodemic.com/?pagename=Media_Portal&primary_category=Artist%20Video&secondary_category=NT4&product_name=Acoustic_Guitar&filename=Portal-Video/Artist%20Video%20HIGH/NT4-Acoustic.wmvClose mic vocals + guitar + others...creative use of the 90 degree config for the lead vocalsit
http://www.rodemic.com/?pagename=Media_Portal&primary_category=Artist%20Video&secondary_category=NT4&product_name=3-Piece&filename=Portal-Video/Artist%20Video%20HIGH/NT4-3PieceA.wmvDistant mic piano + vocals...probably useful as a reverberant mix.
http://www.rodemic.com/?pagename=Media_Portal&primary_category=Artist%20Video&secondary_category=NT4&product_name=Classical_Vocals&filename=Portal-Video/Artist%20Video%20HIGH/NT4-Classical.wmvdigifish