The NMR technicians where I work have recently started replacing the standard 2D NMR experiments (COSY, HSQC) with NUS variants (25% sampling). For the uninitiated, the rationale behind the technique is summarised by Claridge (who does a better job of explaining than I would):
The classical sampling of 2D (and more generally multi-dimensional) NMR experiments requires the uniform sampling of data in the indirect dimension(s) that allows for the processing of the data by the discrete Fourier transform. This means a sequential, stepwise increment of the t1 period of a 2D data set is made to the limit t1 which dictates the resolution in this dimension. The number of such t1 increments employed ultimately defines the total duration of the experiment. The method of non-uniform sampling (NUS) seeks to reduce the number of data points collected in the indirect dimension(s) and so reduces the total experiment time.
Claridge, T.D.W. High-Resolution NMR Techniques in Organic Chemistry, 2016
My experience of these experiments has been overwhelmingly positive so far: shorter experiment times and greater resolution, even when acquiring spectra of small quantities (0.1 - 0.5 mg) of large molecules (ca. 1000 Da).
The challenge is knowing what to do when the spectrum doesn't come out looking quite right. With 'traditional' experiments, running more scans often fixes a multitude of sins (up to a point), but with random point sampling I can't see this holding up so well.
The processing of data is also causing some confusion - TopSpin and MNova give (often very) different results, despite both having NUS processing capability. This processing issue leads me to suspect that many of the issues I'm having with spectra from NUS pulse sequences are actually due to the processing (which isn't terribly well covered in the TopSpin manual).
My question, therefore, is what considerations should be taken into account with NUS spectra: are there instances where its better to take the hit and run a long HSQC? What do I need to be careful of when processing data to ensure spectra come out looking okay?