I have the NT5's and love them. I don't know what the guy in that review that Han posted was talking about...maybe he got a bad pair?? They sound amazing on cello, great on ac guitar, and very good on piano. I have yet to use them as drum overheads (I've been using LDC's for that lately).
And I would have to agree with JamesPierce - I don't see much point to the NT4. If you really need to record a ton of stereo maybe, but even then, with the NT4 you can't chose between ORTF or spaced pair or M/S or XY. You get one stereo "trick" and that's it. The NT5's are great for stereo, and you can pick whatever technique you want to use (well, you'd need a figure-8 for M/S but you know what I mean), and you can split them up for other things as well.