The shortcoming of traditional sampling is usually not in the notes themselves, but the space before, between, and after notes.
One of the cool technologies Orange Tree Samples developed is variable pre-roll samples, which addresses the space before notes to maximize the realism of the attack of notes.
Consider guitar samples, for example. When you play a note on a real guitar, the pick hits the string 50-100ms before actually plucking the note. Also, after hitting the string, the pick creates a quiet scrape noise as it moves across the string. While this sound may appear to be a subtle detail, if you're adding distortion or compression, this detail becomes very audible. Of course, it isn't possible to anticipate the note before it is played, at least for live playing.
Example of guitar sustain including pre-roll sample (Click here to download)
Example with pick approaching string from greater distance (Click here to download)
Sample developers always trim this sound off the sample, to insure there isn't any latency inherent in the sample. What I've done with Orange Tree Samples libraries is to trim this portion of the sample off, but save it as a pre-roll sample file to be used by the sample library's script. The script can use as much or little of the pre-roll sample as needed, generally using as much of it as possible without creating any noticeable latency--all based on your performance, reacting realtime. You can then play the guitar samples live and still get the added realism from these pre-roll samples without having to account for added latency.
This technology is used in our Evolution libraries, CoreBass Pear, Iconic Bass Jaco, and many others.